Anthem STR Duo, Front View
The Anthem STR preamplifier and power amplifier are singular and highly capable components that can form the nucleus of an exceptional stereo music system.
Anthem STR Preamplifier and Power Amplifier
- The preamp is essentially a two-channel processor with onboard DAC, room correction, and digital bass management.
- The preamp has a clean pure-analog mode and a high-quality MM/MC phono section.
- Plenty of digital and analog inputs.
- The preamp has provision to manage and equalize up to two stereo subwoofers.
- The power amp seemingly has plenty of clean power to spare at any volume.
- Both components feel and look expensive.
- Large digital displays are easy to read and look just plain cool.
For the 2-channel audio enthusiast, the level of product innovation hasn’t changed very much over the last few years. Yes, technical specifications of the equipment we use have undoubtedly improved, but these advancements really are incremental at best. Beyond the advent of streaming music and new systems for efficiently digitally archiving and distributing our music collections across a network, the bulk of what comprises stereo audio effectively remains the same. A casual walk through any good audio show like Munich High End or RMAF proves my point. There is an abundance of all the components we are familiar with and need, speakers, amps, preamps, DACs, CD/media players and an astonishing number of turntables as of late. But outside of aesthetic differences and varying degrees of engineering application, the stuff doesn’t break much new ground.
The biggest issue in any music playback chain, outside of the source material that you listen to, is the listening room itself. No amount of money spent on equipment, or the amount of time spent on tweaking speaker positioning, will completely overcome a poor sounding listening environment. The solutions to this age-old vexing problem are the judicious use of room treatments and/or electronic speaker-room correction. Room EQ is available these days in even the lowliest AV receivers, but it is surprisingly scarce in good quality 2-channel audio equipment. Room EQ choices for stereo listeners have, until recently, been limited to affordable, DIY-based solutions from MiniDSP (incorporating DIRAC Live) or more expensive custom solutions from companies like DEQX or Bohmer Audio.
For this review, Anthem Electronics has provided us with their new STR 2-channel preamplifier and matching (beastly) stereo STR power amplifier. The defining feature of the STR preamplifier is the incorporation of a custom version of Anthem’s renowned ARC room correction system combined with complete digital bass management resources. This preamp can allow a user to configure up to a 2.2 channel audio system with either stereo or mono subwoofers. It also has a traditional suite of digital inputs, a high-quality phono section and a low-noise analog line stage with fully analog volume control. The STR power amplifier is a clean sounding, and more robust version of the amp section that is in Anthem’s STR integrated amp. While the STR preamp can be paired with any power amplifier one wants, Anthem sent along the STR power amp to create a perfect synergistic match. It most certainly looks the part!
Anthem STR Preamplifier
2-channel audio preamplifier with DSP and bass management.
Analog Direct In: 10 Hz – 80 kHz (+0.00, -0.10 dB)
Analog In, DSP Mode: 10 Hz – 40 kHz (+0.00, -0.20 dB)
Digital In, 192 kHz: 10 Hz – 50 kHz (+0, -0.5 dB)
Digital In, 96 kHz: 10 Hz – 45 kHz (+0, -0.5 dB)
Digital In, 44.1 kHz: 10 Hz – 20 kHz (± 0 dB
THD+N @ 1 kHz: DSP Mode: 0.001% Digital in, 0.0016% Analog in:
Analog Direct Mode: 0.0016%
(20 Hz – 20 kHz BW, 2 Vrms output)
SNR: DSP Mode:
113 dB (digital-in), 108 dB (analog-in)
Analog Direct Mode: 120 dB
(at 1 kHz, IEC-A, 2 Vrms output)
Maximum Output: RCA:
3.3Vrms (<0.1% THD)
XLR: 6.6Vrms (<0.1% THD)
Phono Input Impedance:
100 Ω (MC), 47 kΩ and 270 pF (MM)
± 0.1 dB (20 Hz – 20 kHz)
61 dB (MC), 41 dB (MM) (1 kHz – volume set to 0 dB)
DSP Mode: 84 dB (MC), 102 dB (MM)
Analog Direct Mode- 92 dB (MC), 110 dB (MM)
(IEC-A, 2 Vrms output)
Phono THD: DSP Mode:
0.002% (MC), 0.0015% (MM)
Analog Direct Mode: 0.002% (MC), 0.0015% (MM)
(at 1 kHz 20 Hz – 20 kHz BW, 2 Vrms output)
Measurement microphone, Mic stand, USB cable, Remote control, Power cord
3-8/9” H x 17” W x 14-5/6” D
Silver or Black
Anthem STR Power Amplifier
2-channel, Class AB
Power Output (per channel):
400 watts @ 8 Ohms (Continuous, 20 Hz – 20 kHz, <1% THD)
600 watts @ 4 Ohms (Continuous, 20 Hz – 20 kHz, <1% THD)
800 watts @ 2 Ohms (3 seconds max.)
Frequency Response (Manufacturer):
20 Hz – 20 kHz, ± 0.1 dB
THD (400 watts):
0.0007% (1 kHz), 0.004% (20 kHz)
SNR (A-weighted, ref. 400 W):
Damping Factor (20 Hz – 1 kHz):
101 dB (100 Hz), 98 dB (10 kHz)
10kΩ (RCA), 15kΩ (XLR)
Input Sensitivity (for 400W into 8Ω):
6-3/4” H x 17” W x 18-1/2” D
Silver or Black
Anthem, Preamplifier, Amplifier, Room Correction, ARC, Preamplifier Review 2019
Anthem STR Preamp, Front ¾ View
Anthem STR Power Amp, Front View
It goes without saying that these Anthem STR separates are some of the most stylish looking pieces of 2-channel gear that I have laid eyes on. Both components have a minimalist, gently sculpted aluminum faceplate that is dominated by a large TFT display. The overall build quality on both units is outstanding, with a solid weight, good material choices, and an appealing tactile feel to each component befitting of their elevated stature.
Anthem STR Duo, On My Audio Rack
Anthem STR Duo, Close-up of Screens
A surprising menu feature that I came across relates to the phono input when you elect to have its signal converted to digital. Besides the ability to pick from 6 pre-RIAA EQ curves (a nod to collectors who own LPs made before RIAA standardization), a “User” option is also available which allows someone to configure their own custom phono EQ curve. In this mode, you are presented with three additional setting options: Bass Shelf, Bass Turnover and 10K De-Emphasis. By adjusting these parameters, a custom curve can be established so, theoretically one can create custom EQ profiles for multiple phono cartridges or LPs via DSP if you choose. If you decide to stay completely analog with your turntable’s output, then RIAA EQ is all you get. The level of tweak-ability afforded to the user is truly extensive.
As I mentioned earlier, the STR preamp will accommodate practically any 2-channel speaker configuration that you can come up with, from a simple pair of monitors or towers to a pair of speakers and a pair of subwoofers (in either mono or stereo configuration). As my reference stereo rig is a 2.2 channel affair that is normally managed with an analog active crossover, I was particularly keen to see how the STR preamp would handle my particular setup. Regardless of the speaker system is connected, the STR preamp uses a custom version of Anthem’s ARC room correction system to manage the speaker room interaction. Having used ARC in my home theater system for the past couple of years I have become familiar with how it works. As a system, it is pretty intuitive to use and, as of a recent update, it is able to correct speaker response from 20 Hz to 20 kHz if you choose.
The preamp has an Ethernet port on the back panel which allows ARC to communicate with the STR preamp over your home network, this is particularly handy when the unit is a distance from the seating area. The port also communicates with home automation systems as well. I was close enough to the equipment where I could plug the included extra-long USB cable from my Windows PC to the back of the preamp. The ARC microphone was also plugged into my PC when measurements were to be taken. Either way, ARC requires a computer to do the measurement, analysis, and uploading of the profiles to the preamp. Another alternative is to use the ARC Mobile App which is available for iOS and Android which allows you to run ARC from your smartphone. Robert Kozel did a detailed walk through of how to use the ARC Mobile App in his review of Anthem’s AVM-60 processor.
Anthem STR Preamp, Rear Panel
Speaking of the back panel of the STR preamp, it has two pairs of balanced XLR inputs and outputs, with a pair of each being dedicated for subwoofers. There is a similar array of unbalanced RCA outputs, numbering three pairs in total. There are four pairs of unbalanced RCA inputs. Two pairs of those can be programmed for HT Bypass use (the same applies to the four XLR inputs as well). The MM/MC phono input stage deserves some special mention. There is a dedicated pair of RCA inputs for both cartridge types. There are no adjustments for cartridge loadings, so you are fixed to the standard input settings of 100-Ohms for moving coil and 47K-Ohms / 270 pF for moving magnet cartridges. I would have liked to have seen a lower fixed capacitance setting as 270 pF might be a little high for some MM cartridges (after factoring in interconnect and tonearm wiring capacitance). Regardless, it is always advisable (if you can) to use phono interconnects with a capacitance rating as low as possible. Too high a level can unduly peak or retard the upper-end response of a given cartridge. On the digital side of things, there are a pair of coax digital inputs, a pair of Toslink digital inputs, a single AES/EBU digital input and an Asynchronous USB input as well. On the operations end, there is also a USB port for updates, a mini-USB port for connecting the computer performing ARC measurements, an RS-232 serial port for automation systems, and a couple of triggering jacks. Anthem supplies the standard ARC “kit” that ships with their MRX receivers and AVM60 pre/pro. The included remote control is a streamlined, all metal, affair that easily accesses all the features of the preamp and quickly becomes intuitive to use.
Anthem STR Preamp, Remote Control
Anthem STR Preamp, Internal View Top
Anthem STR Preamp, Internal ¾ View
Anthem STR Preamp, AK4456VN DAC Chip
Anthem STR Preamp, CS3308-CQZ Volume Control Chip
The quality construction continues on the inside of the STR preamp with well laid out board designs and neatly mounted components. For A/D and D/A duties, Anthem has chosen chips from AKM, specifically the AK5552VN (2 channel) ADC and the AK4456VN (6 channel) DAC respectively. The design also incorporates the AK4137EQ sample rate converter and an 8-channel analog volume control chip from Cirrus Logic, the CS3308-CQZ. These are all fine chip choices and are almost identical to what is used in Anthem’s AVM60 pre/pro and the MRX1120 receiver. However, as a premium audiophile component, I would have expected Anthem to have picked from AKM’s higher level chips or ESS’s new Sabre chips.
Anthem STR Amp, Interior View
Anthem STR Amp, Rear Panel
The STR power amplifier is a sight to behold both inside and out. Its exterior design and construction matches the quality and attention to detail of the STR preamp, just on a larger scale. The power amp’s 7-inch TFT display’s main party trick is to digitally simulate two huge ballistic VU meters. Who doesn’t love a pair of big VU meters on their power amps! The meters can be set to accurately show power into 8, 4 or 2-ohm loads as well as displaying current operating temperatures for each channel. The rear panel has both balanced and unbalanced inputs, a pair of robust 5-way binding posts per channel, a USB input for firmware updates, and a pair of trigger jacks with toggle switches to set their operation. Looking at the internals, it is a Class AB, dual mono design rated at 400, 600 and 800 (3 second burst) watts into 8, 4 and 2 ohms respectively, with both channels driven. The amp’s linear power supply starts with a pair of 600VA toroidal transformers, one per channel. Each channel has 32,800 uF worth of power capacitors and 16 output devices per side. The STR amp uses a cascoded complementary feedback input stage which, Anthem claims, creates a sound quality similar to Class A amplifier designs but with much greater operating efficiency. In place of rail fuses, Anthem uses advanced DSP to monitor the amplifier’s output conditions and help guard against high operating temperatures and other fault conditions.
On appearances alone, the STR amplifier certainly looks the part, and while I have no way to measure the amp’s actual output, I would be very surprised if it didn’t meet its rated specs handily based on the quality of construction and parts used.
Anthem STR Duo with Paradigm Persona 7F Speakers
Anthem STR Duo with BESL Monitors and Dual Subs
Connected source equipment included an OPPO BDP-105D universal player, a Technics SL1200 mk6 turntable (that has been modified by KAB Electroacoustics) equipped with an Audio-Technica OC9/MLII moving coil cartridge, and a Surface 3 Pro tablet (via USB) using J River Media Center 24 playback software. In terms of speakers, I alternated between a pair of Paradigm Persona 7F loudspeakers run full range, and my BESL (Bamberg Engineering Sound Lab) Series 2 MTM monitors crossed to my two DIY 15-inch sealed subwoofers (each in 4.5 cubic ft enclosures) for a 2.2 channel system. For both speaker configurations, the main speakers were 9 feet apart with the main listening position being 10.8 feet away. The subwoofers, when used, acted essentially as bass stands under my BESL monitors so they were both 10.6 feet from the listening position. The monitors were crossed over to the subs at 80 Hz. I used two Dayton Audio SA1000 subwoofer power amplifiers to run my subs when they were in play.
When running the ARC calibration for each speaker system, Anthem recommends a minimum of 5 measuring points, the first being at the main listening seat and the others made at least 2 feet away from the first measurement position. Anthem/Paradigm kindly dispatched their Central Regional Manager, Joey Perfito, to walk me through initial setup of the STR duo in my studio space. For my listening area, Joey recommended I make measurements at a 3-foot distance from the main seat. For our initial setup Joey felt that 5 total mic measurements would be sufficient for my needs. In later weeks I would make additional ARC runs with up to 8 total measurements with the results varying minimally from the initial establishing run. Be forewarned, the ARC calibration tones are loud, roughly 80+ dB in level. Once all the measurements are done, the system normalizes everything to the 75 dB range. For an in-depth look at how the ARC system works, please refer to our definitive Geeks Guide to ARC 2 and Super Geeks Guide to ARC 2 both put together by Dr. David Rich.
I’ve already made mention of the top-shelf build quality and unique design of these STR components. Simple things, like the weight of the units as you install them into your system or the smoothness and feel of the volume control as you dial it in, tell you that you are dealing with very special items that have been designed with care. The large TFT displays on both components make for outstanding readability and usability from across the room. It’s a stylistic concept that European manufacturers regularly use, and I saw a lot of it while at the Munich High End show. Anthem’s execution of the display interface is crisp, clear and logical, but feels decidedly like a different aesthetic altogether – a Canadian design language perhaps. The thing is, once you get used to the convenience of such displays, it’s hard to go back to gear with little dot-matrix readouts or nothing at all. I’m talking about you Marantz with your silly little porthole scheme!
I started off by using the Paradigm Persona 7F loudspeakers hooked up and playing full range with the STR duo. ARC automatically defaults to a flat EQ profile with an upper limit of correction set at 5 kHz and ARC detected a modest level of room gain dialed in below 300 Hz. As you can see in the image, the Personas have good extension down to 25 Hz in my room. Oddly, ARC still does not automatically set the speaker distances; you must do that manually post measurement. After listening to those initial results, which were notably more linear but a little bass-shy for my tastes and also missing a little of the added presence in the vocal region, I experimented with a few changes that got the sound more to my liking.
I started by bringing ARC’s correction limit down to 300Hz. This allowed ARC to focus on the bass response while allowing the bulk of the Persona’s sound, which I already liked in my room, to remain untouched. And, barring any serious room acoustic issues, if you are spending the kind of money that buys a pair of speakers like these, you hopefully are doing so because you like the way that they are voiced to begin with. I also elected to bump up the Room Gain setting from 1.5 to 4 (5 sounded fun for some tracks but was too much for a broad range of music) and went for a steeper roll-off (6th order) at 25 Hz. This helped even up the lowest reach of both the speakers while matching the natural roll off imposed by the room. The resulting sound was absolutely spectacular. The Personas sounded good in this room already but now, any hint of boominess to the bass had been filtered out and yet there was still a tight and visceral impact to the bottom end. Basslines in some of my favorite hard rock songs now had tautness to their tone but would still create a palpable floor of sound that could rumble ferociously when called upon.
ARC had effectively corrected the biggest problem area in the room (within its acoustic capability) and allowed me to extract the best performance possible out of an already stellar pair of speakers. The STR amplifier was a perfect match to the Persona 7Fs. It had no obvious sonic faults that I could pick up on and it maintained the revealing nature of the speakers without allowing them to sound ruthless. It also had a seemingly endless reservoir of drive that allowed the speakers to perform at their best, regardless of volume level.
As revealing as the Persona 7Fs are, I was curious to see if they would pick up any residual noise in the preamp. Well, either in full analog mode or with ARC and A/D signal conversion engaged, cranking the volume wide open, with no input signal, gave me nothing but silence. Only through the phono inputs was I able to get the slightest wisp of a noise floor at full volume, but I had to be practically kissing the speaker to hear it. Another interesting experiment involved setting up a series of phono inputs to compare and assess the sound quality of the STR preamp’s processing versus having none at all. One input was set up as a pure analog signal path, I configured another with just the A/D up-conversion, and then a third with A/D conversion and ARC enabled as well. I was able to independently adjust the gain of each input until they were all matched and then it was a simple matter to cycle through each of the three inputs, via remote, with an album playing and compare the sound between them. Note however that the pure analog signal path bypasses all bass management so any subwoofers you have in the system will be silent and your main speakers will operate at full range. It became quite clear after repeated listening that the A/D conversion and processing that Anthem was employing in the STR was as transparent as I have yet come across in a digital component. I didn’t think I would like the sound of vinyl converted to digital and I was sure there would be some inevitable loss of warmth or body in the process. But after weeks of listening, that preconceived notion was put squarely out of its misery and I found myself preferring to listen to my vinyl with ARC engaged. I was converted. The benefits of the advanced room correction were too great to not have, even when listening to moldy old vinyl. Sacrilege!
After a few weeks, I decided to switch gears and traded out the Paradigm floor standers for my usual 2.2 setup consisting of a pair of BESL Series 2 MTM monitors crossed over to a stereo pair of DIY 15-inch sealed subwoofers. The measurement procedure was the same as with the Personas, the only difference being my needing to tell ARC that there were 2 subs now in line and whether to treat them as a mono or stereo pair. My practice in the past has been having these subs operate as a stereo pair since their individual responses closely match, so I elected to continue that here.
As you can see, ARC defaults to achieving the flattest overall response up to 5 kHz while applying a modest level of 2.125 Room Gain. Things sounded good overall, but the bass was noticeably tamer than I wanted.
After “seasoning to taste” I brought the correction limit down to 400 Hz and bumped up the Room Gain to 4.5. Much better to my ears! The monitors maintained the imaging and liveliness that I liked about their sound but now the subwoofers were more seamlessly integrated into the whole. The extra tweak of Room Gain brought back that additional impact that made everything sound better. My subs now sounded cleaner with all the extension and power that my room would allow. It becomes much more fun for me to listen to something like the “Summer Presto” movement from Vivaldi’s The Four Seasons. Where I once felt just a sense of bass coming from cellos and the lower octave stringed instruments, I now have this churning wave of bass floor that that adds so much more depth and dimension to the performance. And it doesn’t sound thick, noisy or overwrought, it sounds tight, tangible and right where I want it to be. Within ARC’s controls, it’s very tempting to go crazy with the Room Gain setting, particularly when dialing in subs. ARC only allows a maximum Room Gain setting of 6 and maxing it out makes the bass sound muddy with music and just defeats the purpose. Finding that right balance where the desired bass level remains tight but impactful may take a little patience and extended listening to achieve.
There were times during my preliminary set up that I easily thought that the bass was where I wanted it to be, but a couple of days later it felt like it was too much, and I dialed it back. Anthem suggests that you take your time and listen to your newly calibrated system to become attuned to how everything sounds, and it is wise advice to heed. That being said, this is also about enjoying your music and your personal preferences play a part in that. So, don’t be afraid to experiment, just do it carefully. ARC may not give you the kind of granular control over the EQ curve that DIRAC LIVE or even Audyssey’s new Curve Editor App allow, but the available controls are plenty powerful, and the results do sound mighty sweet when you get things set just right. Again, the STR power amp could not have sounded better with my BESL monitors. These speakers present a consistent 4-ohm load and the STR amplifier just kept them well fed and cruising right along. There were a few times where I listened to vinyl in pure analog mode, which bypassed the subs and had these sealed monitors running full range. I was actually rather surprised at how much bass I was getting from the BESL’s twin 7-inch drivers alone. It wasn’t earth-shattering by any stretch, but it was more than I’d ever heard with other amps running these speakers without a crossover. This was definitely a tip-of-the-hat to the STR amp’s power reserves.
The following are a few notable musical selections that I felt showed off the Anthem STR duo during our time together:
Melody Gardot, My One and Only Thrill, CD
Melody Gardot “My One and Only Thrill”
Melody Gardot, My One and Only Thrill, Verve CD.
While Diana Krall has become one of the most often heard female vocalists when it comes to demo material at audio shows (for better or worse), I find Melody Gardot to be just as good, if not better, a musical gauge in this regard. The up close and intimate presentation of her vocals and many of the lush orchestrations make for the perfect material to get lost in, while listening through a good pair of speakers.
Listening to the opening track “Baby I’m a Fool” through the STR duo and the Persona 7F speakers made for a heavenly combination. The sheer detail and level of dynamics delivered by the STR preamp and amp were simply outstanding. Miss Gardot’s voice was rendered with a sweet, almost liquid quality that just drew me into the music, while the band with the background strings unfolded into this broad and deep musical image. ARC was performing its due diligence helping keep the acoustic bass lines sounding full yet articulate throughout the song. There are also these lovely little details like the sounds of her fingers moving across the guitar strings and the hollow tapping sound of her hand on the body of the guitar that this ensemble of gear just gets so right. Moving to the more R&B tinged “Who Will Comfort Me”, ARC once again delivers tight and meaty sounding acoustic bass lines through the Personas which, without acoustic correction, would otherwise sound peakier and more bloated in this room. And once again, Miss Gardot’s voice is just about perfectly imaged, dead center, with the very tasteful sounding horn section accenting her delivery with precision. The muted trumpet solo is particularly rich with character and detail. In listening to this system, if nothing else, one gets a proper appreciation of the synchronicity that is possible when electronics and speakers are ideally matched.
The Music of Batman, Silva Screen Records, CD
The City of Prague Philharmonic Orchestra “The Music of Batman”
The City of Prague Philharmonic Orchestra, The Music of Batman, Silva Screen Records, CD.
Moving to my 2.2 channel setup, I listened to a very dynamic orchestral recording of selections from the various Batman films. All these tracks feature great renditions of this material and the orchestra itself is well recorded with noticeable hall ambiance and a big, detailed soundstage throughout. The STR amplifier had no trouble keeping up with the dynamics and volume swings regardless of the level I was listening to.
This helped make my BESL monitors sound as controlled and musical as I’ve ever heard them. A number of the tracks from the films prominently feature tympanis or bass drums being played with abandon. One track in particular, “Aggressive Expansion” from The Dark Knight, is a monster in this regard. Just after the opening 15 seconds, an intense barrage of bass drums establishes the underlying beat for the passage and my ARC corrected subwoofers were hitting commensurately hard. They were replicating not just the impact of the drum hits, which was significant, but the tightness and tonality of the drum skins were coming through clearly as well. As the track continues, an almost subterranean floor of bass transmits through the room and, normally, it would sound like more of an amorphous tone that would loudly resonate with the walls. With ARC in play, the room resonance is sharply reduced and the bass sound became more focused and melodic while retaining the desired impact. This is the sort of musical material that can just shine with a good subwoofer. Having two properly calibrated subs playing this stuff is just outstanding!
Elvis, Elvis Is Back, 45 RPM LP
Elvis “Elvis Is Back”
Elvis, Elvis Is Back, RCA/Analogue Productions, 45 RPM LP.
Staying with the 2.2 channel rig, I loaded up this Elvis classic that had been remastered by Analogue Productions. I had heard some tracks from this album in a very high-end equipped room at this past Munich Audio show. It was clear that this room had been properly set up and (passively) acoustically treated.
I remember marveling at how good and lifelike “The King” sounded in that setting. It almost gave me shivers. Listening to Elvis’ rendition of “Fever” in my studio with the Anthem STR components brought me that same feeling again. Yes, there is a ton of artificial reverb in this track, but so what? The overall ambiance from the song was big and enveloping, the simple finger snaps that marked the beat just sounded crisp and were full of dimension, and the notes from the acoustic double-bass were deep and very tight sounding. “Soldier Boy” which is structured like a classic doo-wop tune comes out sounding very full, with significant depth to the presentation. Elvis’ voice is parked dead center and he gets to flex his range a little bit on this one. At no point did his voice sound unnatural or lacking at all. His backup singers, The Jordanaires, were imaged to the right and behind him, filling in the soundstage nicely but not overpowering the main man. Electric bass was suitably deep and punchy without any artificial bloat. While this wouldn’t be an overly demanding song for the Anthem’s STR duo, its playback with these components sounded especially well put together and was presented seamlessly across two speakers and two subs. Can’t ask for better than that! The STR preamp’s phono stage mated well with my Technics turntable and Audio-Technica OC9/ML II moving coil cartridge. I was able to adjust the MC Phono input level a touch and raise the gain by a few dB to get a good, noise-free, overall playback level.
Getz/Gilberto, Verve Records, DSD Files
Stan Getz and Joao Gilberto “Getz/Gilberto”
Stan Getz and Joao Gilberto, Getz/Gilberto, Verve Records, DSD Files.
I hooked up my Surface 3 PRO tablet, via USB, to the STR preamp and downloaded/installed the requisite ASIO driver from Anthem’s website in order to try out playing some DSD files direct to the DAC. Getz/ Gilberto is a classic and a consistent favorite of mine due to the artistry and the impeccable sound quality.
Anthem’s STR duo did not disappoint. Right from the start of “The Girl from Ipanema” the preamp’s DAC latched on to the 2.8 MHz DSD bitstream without issue and played back the music splendidly over my 2.2 channel rig. The clarity of Joao Gilberto’s acoustic guitar playing in the right channel along with Stan Getz’s saxophone coming from the left was as good as I’ve ever heard it, perhaps better in some respects. And the close mic-ing of Gilberto’s vocals came across in a beautifully detailed presentation. Low distortion electronics and substantial power on tap no doubt have something to do with that. Astrud Gilberto’s famous, slightly haunting, vocals also come from the right but are placed further back, adding to the sense of depth. Acoustic bass sounded properly solid with plenty of weight, ARC doing its thing here to banish the acoustic bloat. On the track “O Grande Amor,” Stan Getz’s opening saxophone solo just floated right in front of me, replete with all the textural detail that I could ask for. Full of dynamics and without a hint of harshness. The rest of the track was a supportive and balanced concoction of piano, acoustic guitar, bass, and cymbals. Very smooth sounding but the details in each instrument were fully discernible and didn’t sound smeared in any way. As an operational note, I encountered none of the connection “hiccups” that can sometimes occur with DSD playback from a computer. The USB connection remained solid and stable throughout. No clicks or unexpected pops when switching tracks.
Gene Ammons, The Boss is Back! LP
Gene Ammons, The Boss is Back! Prestige LP, 1969.
Going back to the Paradigm Persona 7F and some vinyl, the soothing sounds of this Gene Ammons record certainly fit the bill. Cueing up the track “Feeling Good” turned out to be a good primer on Ammons range with the tenor sax which alternates from a smooth sounding groove to aggressive punctuations of tone.
His sax playing came across more detailed with a leaner sounding tone than what I previously heard on the Getz/ Gilberto album, but still with plenty of dimensionality and body to the sound. The Fender bass setting the pace through the track sounded impressively low and tight coming from a piece of vinyl birthed in the same year as I was. An organ weaves in an out with the bassline providing a very grooving foundation. Moving on to “Tasting the Jug”, the sound of the acoustic bass and congas are especially noteworthy. With ARC turned off, the bass got bloated and a little mushy sounding. The congas got a little leaner and lost some of the dimension to the sound of the skins. Engaging ARC sorted that out; the bass got solid and tighter sounding while keeping the desired depth. The congas sounded more like they should, with added weight returning to their sound. Everything else that fell above the ARC EQ cutoff sounded, subjectively, as close to identical between being in pure analog mode and converted to digital for processing. I couldn’t reliably tell a difference.
As you’ve no doubt surmised, I really like these Anthem STR separates. For 2-channel playback, I think the preamp has been carefully tuned and refined to be an incredibly effective front-end solution. It’s got a fantastic room correction system, effective and flexible bass management, very low noise, an overachieving phono section, a very good A/D and DAC section, tons of inputs, great looks and build quality and I can go on. The STR amp is about as good a 2-channel amplifier as you are likely to find for all practical purposes. It’s got low noise, plenty of transparency, scads of power reserve capability, impressive build and, by Odin’s beard, those huge meters are awesome! So, what’s the catch? I would have to say the price. Less so for the amplifier because comparable products from companies like ATI, Bryston and such are in that ballpark.
The preamp, on the other hand, has an MSRP that is $1000.00 more than the AVM60, for a 2-channel preamplifier that essentially has the same A-D and DAC section and no HDMI inputs. Yes, it is beautifully engineered, has a dynamite phono input and, realistically, I’m sure I probably wouldn’t hear a difference with better digital chips (you can tell in the measurements that Anthem has spent some time getting the best out of the silicon they are using), but I really wish this thing had an HDMI input so that I could directly pass a DSD bitstream over from my OPPO (or any other) HDMI equipped player. I may be in the minority, but I almost never use a USB input, it’s too impractical for me and I would gladly give it up for a properly implemented HDMI input. My nitpicking may sound a bit on the irrational side, but these are billed as audiophile components and, for the money spent, an audiophile looks for state-of-the-art, even if sometimes it’s only for bragging rights. But, back in the real world and with all my grousing aside, the STR preamp is an incredibly transparent piece of equipment and the ARC room correction is the linchpin. It allows me to extract the best performance and all the potential of any speaker and subwoofer combination that I could bring into this room. That alone makes it rather invaluable in my estimation.
When Carlo told me how much he had been enjoying the Anthem STR Preamplifier and STR Power Amplifier combination in his listening room, I became really curious to hear how the pair would sound in my existing home theater. Fortunately, Carlo and I live just a few hours away from each other, so after checking with Anthem, I picked up the STR gear from Carlo and eagerly looked forward to auditioning them in my home.
The STR Preamplifier provides Home Theater Bypass functionality for both the front left and right channels as well as two subwoofers. The connections to the STR Preamplifier can be made using either RCA or XLR inputs or a combination of the two which is what I used in my listening room. My reference home theater processor is the Anthem AVM 60. I connected the front left and right channels from the AVM 60 using the XLR inputs on the STR Preamplifier and I connected the two subwoofer channels using the RCA inputs. Using the Configure HT Bypass menu in the STR Preamplifier, I set the Fronts to use “XLR1” and the Subs to “RCA4”. This left the second XLR input on the STR Preamplifier available for connection to my Oppo UDP-205 4K UHD Blu-ray player which was also connected via HDMI to the AVM 60. The choice of connection type is a user preference, but I like to use balanced connections when available since they offer common mode noise rejection. I connected the STR Power Amplifier to the STR Preamplifier using balanced interconnects. The next step was to connect my front speakers, which are GoldenEar Technology Triton Reference, to the STR Power Amplifier. I connected the subwoofer outputs from the STR Preamplifier to the built-in subwoofers in the Triton Reference speakers. Once all the connections were made, I made sure to use the Level Calibration menu on both the STR Preamplifier and on the AVM 60 to make sure that I had properly connected each channel.
With the connections out of the way, the next thing to consider was room correction. I ran Anthem Room Correction (ARC) once using the STR Preamplifier for my front left and right and subwoofer channels. I then ran ARC again just for the AVM 60 home theater. In this configuration, the STR Preamplifier was in standby mode and the front channels and subwoofer inputs were seamlessly connected via relays in the STR Preamplifier to the AVM 60. This may sound like a lot of work, but it offers an amazing amount of flexibility in terms of configuration. For example, two subwoofers can be configured as a stereo pair using ARC in the STR Preamplifier, but they can only be configured as a mono signal on the AVM 60.
From an operational perspective, the one consideration was how to conveniently power on the STR Power Amplifier. While the amp supports 12-Volt trigger operation, there is unfortunately only one 12-Volt trigger on the AVM 60 and that was used to power on one of my theater amps. The simple answer was to configure the STR Power Amplifier to use Audio Detect Mode. Setting this option to “Yes” allows the amp to automatically turn on whenever a signal is detected. It automatically turns itself off once a signal is absent for a period of time.
With the configuration out of the way, I don’t think I was quite ready for how good this sounded in my system. The STR Power Amplifier made the Triton Reference speakers, which already were amazing in my room, sound breathtaking. This was the case when listening to both stereo through the STR Preamplifier and when listening to movies through the AVM 60. While I was always content with the sound using my McIntosh MC8207 seven-channel amplifier, introducing the Anthem STR Power Amplifier into the system to power the Triton Reference speakers was transformative. For example, in listening to Sir Colin Davis and the London Symphony Orchestra performance of “Holst: The Planets”, the separation of sounds between the horns and percussion was richly detailed. The attacking bass performance on the track “Mars” was palpable and precise thanks to the Triton Reference and Anthem Room Correction on the STR Preamp. The multi-layered sound of the orchestra was never fatiguing even when listening at higher volumes.
I was impressed with how the STR Preamplifier and STR Power Amplifier handled female voices. The nuances of the female harmonies on the track “Time” from the Delicate Balance album “Driftwood” were noticeable. The rich layers and sounds of the keyboard punctuating “Hey Nineteen” from the Steely Dan “Gaucho” album sounded wonderfully alive. The separation of instruments and amazing sense of detail in Howard Shore’s score “The Lord of the Rings: The Fellowship of the Ring – The Complete Recordings” has never sounded better in my room. The combination of the Triton Reference and STR gear enveloped my room in the sound of this magnificent score and revealed endless nuance that had previously gone unnoticed.
When listening to movies or television, I simply turned off the STR Preamplifier which puts the unit into standby and closes the relays to complete the Home Theater Bypass. The approach worked exceedingly well and I never experienced any type of lip-sync delay problems. I should also note that the Home Theater Bypass functionality can be used with any brand of home theater receiver or processor.
Carlo has already covered his listening impressions with the STR Preamplifier and STR Power Amplifier, and I don’t think I have anything else to add except to say that the impact on home theater soundtracks when paired with the AVM 60 is equally impressive. I hope Anthem comes up with multi-channel versions of the STR Power Amplifier sometime soon.
In terms of telling a difference between the AVM 60 and the STR Preamplifier when it comes to sound quality, I would be hard pressed to tell you that I could reliably pass a blind listening test in that regard. The sound quality was excellent whether listening from the AVM 60 or from the STR Preamplifier. I really enjoyed listening to the STR Preamplifier since it brought back fond memories of the Anthem Statement D2v 3D which was Anthem’s flagship A/V processor for many years. While the STR Preamplifier still includes technology like up-sampling of lower-resolution sources, the STR Preamplifier has eclipsed the D2v 3D with features like MM and MC phono inputs, asynchronous USB supporting 32-bit/384kHz PCM and DSD 2.8/5.6 MHz sources, pre-RIAA curves, and stereo bass management.
To Carlo’s point about the lack of HDMI inputs on the STR Preamplifier, I think it comes down to how you choose to connect sources to the STR Preamplifier. In my case, I didn’t need an HDMI input on the STR Preamplifier because I could make use of the inputs on the Oppo UDP-205. There is also the asynchronous USB input on the STR Preamplifier which supports DSD. It is also reassuring to know that the STR Preamplifier doesn’t have to be updated when the HDMI standard changes. While the STR Preamplifier is expensive at $3,999, combining it with the AVM 60 at $2,999 for a total of $6,998 is still far cheaper than the price of $9,499 for the original Anthem D2v 3D.
Benchmark audio tests were conducted on the RCA and XLR analog inputs and the SPDIF and USB digital inputs of the Anthem STR preamplifier. Various custom digital test tones were sent through the Anthem using an OPPO BDP-105D or a Microsoft Surface PRO 3 as the source and measured with SpectraPLUS audio measurement software via a LYNX TWO B professional sound card. Testing the RIAA tracking ability of the phono stage and overall frequency response of the preamp was done in a similar manner, but the test tones and sweeps were provided by the built-in signal generator within the SpectraPLUS software. Measurements taken at the unbalanced RCA outputs were performed at a 2 Volts RMS (6.02 dBV RMS) reference level while the balanced XLR outputs were measured at a 4 Volts RMS (12.04 dBV RMS) reference level. Unless otherwise stated, most measurements were taken from the balanced XLR outputs. I do not currently have the resources to bench test power amplifiers so the analysis on the STR power amplifier is strictly subjective.
1 kHz 16/44 Sine Wave at 0 dBFS SPDIF-In RCA-Out, 2 VRMS
Starting with the basics using the SPDIF digital input, a 16-bit/44 kHz, 1 kHz sine wave produces a THD+N of 0.001106% at 2 Volts measured at the RCA outputs. Overall response is clean with two very minor harmonics at 2 and 3 kHz registering at 100 dB below 2 VRMS.
1 kHz 16/44 Sine Wave at 0 dBFS SPDIF-In XLR-Out, 4 VRMS
Here, a 16-bit/44 kHz, 1 kHz sine wave produces a THD+N of 0.000812% at 4 Volts measured at the XLR outputs. Again, a clean response with two minor harmonics at 2 and 3 kHz registering at 94 and 97 dB below 4 VRMS respectively.
1 kHz 24/96 Sine Wave at 0 dBFS SPDIF-In XLR-Out, 4 VRMS
Using a 24-bit/96 kHz, 1 kHz sine wave produces a THD+N of 0.000645% at 4 Volts measured at the XLR outputs. Not much in the way of noise spurs but a few harmonics show up through the spectrum. The harmonics at 2 and 3 kHz registering again at 94 and 97 dB below 4 VRMS respectively.
1 kHz 24/192 Sine Wave at 0 dBFS SPDIF-In XLR-Out, 4 VRMS
24-bit/192 kHz 1 kHz THD+N looks almost identical to the preceding test with a result of 0.000639% at 4 VRMS. The noise and harmonics profile also appears identical to the 24/96 test.
19 & 20 kHz 24/96 Sine Wave at -5 dBFS SPDIF-In XLR-Out, 4 VRMS
Here are the results for the 19 kHz, 20 kHz combined test frequencies using the SPDIF coax input with 24-bit/96 kHz sampling at 4 VRMS. We see some distortion spurs throughout the spectrum. There is a visible B-A peak at 1 kHz at over 100 dB below each test tone at 4 VRMS which is insignificant. The second harmonics at 38 kHz and 40 kHz are about 90 dB respectively below 4 VRMS.
1 kHz 16/44 Sine Wave at 0 dBFS USB-In XLR-Out, 4 VRMS
Switching to the USB input, a 16-bit/44 kHz, 1 kHz sine wave produces a THD+N of 0.000697% at 4 Volts measured at the XLR outputs. Again, a clean response with two minor harmonics at 2 and 3 kHz registering at 94 and 95 dB below 4 VRMS respectively.
1 kHz 24/96 Sine Wave at 0 dBFS USB-In XLR-Out, 4 VRMS
Using a 24-bit/96 kHz, 1 kHz sine wave produces a THD+N of 0.000654% at 4 Volts measured at the XLR outputs. A few harmonics show up throughout the spectrum, with the harmonics at 2 and 3 kHz registering again at 94 and 96 dB below 4 VRMS respectively.
1 kHz 24/192 Sine Wave at 0 dBFS USB-In XLR-Out, 4 VRMS
24-bit/192 kHz 1 kHz THD+N looks almost identical to the preceding test with a result of 0.000666% at 4 VRMS. The noise and harmonics profile also appears identical to the 24/96 test.
10 kHz 24/96 Sine Wave at 0 dBFS USB-In XLR-Out, 4 VRMS
At 10 kHz with a 24-bit/96 kHz sampling rate, the THD+N was 0.001241% at 4 VRMS. The second harmonic at 20 kHz is about 94 dB below 4 VRMS.
1 kHz 24/96 at 0 dBFS XLR-In XLR-Out Analog Direct, 4 VRMS
Moving now to examine pure analog performance via the XLR inputs, a 24-bit/96 kHz, 1 kHz sine wave produces a THD+N of 0.000737% at 4 Volts measured at the XLR outputs with all digital processing disabled. Minimal noise and a few harmonics show up throughout the spectrum, with the harmonics at 2 and 3 kHz registering again at 92 and 100 dB below 4 VRMS respectively.
1 kHz 24/96 at 0 dBFS XLR-In XLR-Out, A-D DSP On, 4 VRMS
Repeating the same test but, this time, allowing the STR preamp to convert the incoming analog signal to digital (no ARC) allows us to examine how the signal integrity is maintained before any room correction processing. Comparing these results to the previous Analog Direct results show minimal variation. The main differences being about a 3 dB higher noise floor and a slightly better distortion result for this test. In real terms, this difference would be inaudible.
1 kHz 24/192 at 0 dBFS XLR-In XLR-Out Analog Direct, 4 VRMS
Using an analog 24-bit/192 kHz, 1 kHz sine wave produces a THD+N of 0.000756% at 4 Volts measured at the XLR outputs with all digital processing disabled. We see an almost identical noise and harmonic profile to the 24/96 test.
1 kHz 24/192 at 0 dBFS XLR-In XLR-Out, A-D DSP On, 4 VRMS
As with the 24/96 test, converting the incoming analog signal to digital raises the overall noise floor by about 3 dB and actually improves the THD+N figure to 0.000566%. Once again, these are inaudible differences.
10 kHz 24/192 at 0 dBFS XLR-In XLR-Out, Analog Direct, 4 VRMS
At 10 kHz into the XLR input, THD+N was 0.001135%. The second harmonic at 20 kHz is about 90 dB below 4 VRMS.
10 kHz 24/192 at 0 dBFS XLR-In XLR-Out, A-D DSP On, 4 VRMS
Repeating the test with the digital conversion on, THD+N becomes 0.001476%. The second harmonic at 20 kHz is now at 92 dB below 4 VRMS and the noise floor rises by 3 dB again. The third harmonic rises a little and we see a couple of tiny sidebands show up around the 10 kHz fundamental.
20 kHz 24/192 at 0 dBFS XLR-In XLR-Out, Analog Direct, 4 VRMS
At 20 kHz into the XLR input, THD+N was 0.001785%. The second harmonic at 40 kHz is about 86 dB below 4 VRMS. There are some noise spurs out past 45 kHz but the loudest is at 100 dB below 4 VRMS. There also appear to be a pair of tiny sidebands around the fundamental.
20 kHz 24/192 at 0 dBFS XLR-In XLR-Out, A-D DSP On, 4 VRMS
Repeating the test with the digital conversion on, THD+N becomes 0.005785%. The second harmonic at 40 kHz is now at 86 dB below 4 VRMS and the noise floor rises by 3 dB again. The noise at 45 kHz rises by a hair and we see a few more small sidebands show up around the 20 kHz fundamental.
Anthem STR Preamp Frequency Response, Analog Direct
I measured the frequency response of the STR preamp out to 96 kHz. In analog direct, the response is flat until we see a very gradual 6 dB roll-off as we approach 90 kHz. The little dip past 20 kHz is an artifact of my measuring setup.
Anthem STR Preamp Frequency Response, A-D DSP On
We repeat the same frequency response sweep but now with the incoming signal converted from analog to digital by the STR. ARC remains off for this test. We see an identical response up to 60 kHz where a very gentle roll off just begins to start. We lose 3 dB by 80 kHz, another 5 dB by 90 kHz and then drops like a stone after that. In real life, these sweeps would sound identical. The STR preamp’s A-D conversion stage looks to be doing its job very well.
Anthem STR Preamp Frequency Response, A-D DSP and ARC On
One more sweep, this time with an ARC profile from the Paradigm Personas loaded up. Unlike some room correction systems in other AVRs that downsample to 48 kHz, we can see here that the ARC implementation in the STR is indeed processing at 192 kHz.
Anthem STR Preamp DAC Line Linearity
As I don’t have an instrument that automatically measures DAC linearity, I plotted this chart that is culled from a series of progressively lowered 24bit 1kHz tones. An ideal linearity measurement would show a perfectly diagonal line from 0 dB down to the DAC noise floor, indicating that measured DAC output level is identical to signal input level. As you can see the AKM AK4456VN DAC of the STR preamp starts to exhibit trace levels of linearity error before it hits its noise floor at -140 dBFS.
Anthem STR Preamp DAC Relative Linearity
This Relative Linearity chart allows us to examine the above-mentioned errors in a more exaggerated, and easy to see manner. Here we see that the STR preamp’s DAC exhibits minor levels of linearity error starting at -80 dBFS, becoming more noticeable at -120 dBFS and then turning more significant at -130 dBFS, before hitting the DAC noise floor at -140 dBFS. In real terms, these levels of linearity error would be inaudible.
RIAA Phono Playback EQ Target
This is a representation of the RIAA phono playback equalization curve, plotted onto a graph. Due to the physical limitations of the vinyl LP, during the mastering stage, bass frequencies are attenuated by up to 20 dB at the lowest end and treble frequencies boosted by up to 20 dB at the highest end, essentially the inverse of this plot. You can liken it to an early analog form of ZIP compression. This process allows grooves of any frequency to be cut adequately and fit on an LP master. Any phono preamp must administer this EQ curve (or decompression, referring to the ZIP analogy) to any signal coming in from a turntable in order for the music to be reproduced correctly. The closer a phono preamp can match this target curve, the more accurate the musical result.
Anthem STR RIAA Phono Playback EQ Results
Using the MM input and precise test tones generated by SpectraPLUS, I’ve plotted the left and right channel RIAA tracking response for the STR preamp’s phono section and overlaid them on the target plot. As you can see the phono performance is extremely good, tracking the RIAA target very closely. The 1 dB deviation at either end of the spectrum is due to a limitation of my test setup. As a self-contained solution on a preamp, this is outstanding performance.
STR Duo, Black, and White
If you have the means, it is hard to imagine needing anything other than these ANTHEM STR separates to command a 2-channel system of the highest possible quality.
- Beautifully built and engineered components.
- Fantastic phono section and excellent digital performance.
- Tons of clean and seemingly unending power.
- ARC room correction and complete bass management for a variety of installations.
- Those meters…. oh, those meters!
- HDMI, HDMI…. Oh, and did I mention HDMI?
- For the money, a more state of the art A/D D/A solution.
The Anthem STR preamplifier and amplifier are every bit the statement 2-channel products that they are billed as. Individually, they are some of the very best sounding examples of their respective categories. Together, they comprise as seamless and powerful a playback chain as you are likely to find. The STR power amplifier is quite simply a handsome looking beast that should handily drive any speaker load that you can devise. It reeks of quality, both in build and of sound, plus those huge digital VU meters are the slickest looking thing I’ve seen on an audio product. The STR preamplifier is probably one of the more useful and compelling pieces of 2-channel audio equipment to come out in some time. It successfully takes all the essential analog and digital elements of a top-notch stereo front end and successfully mates them to the almost practical necessity of an advanced and flexible room correction system with proper bass management. While not technically perfect, in real-world terms it is almost an indispensable component for the modern-day audio enthusiast. Yes, it is not inexpensive, domestically designed and manufactured products like this almost never are, but it is a quality item and I imagine we will see more components like it arriving soon from other manufacturers.
I think more and more people are coming to the inevitable understanding that correcting the room makes a bigger and more noticeable sonic difference than higher bitrates, expensive cables, MQA or any of the other things that are more like “crumbs on the acoustic periphery”. On a side note to the fine folks at Anthem/Paradigm, I can easily see the STR preamp, with not too much modification, become the control center for a range of fully active speaker systems. Imagine, for example, a set of Paradigm Persona 7F speakers coming from the factory with no passive crossovers, everything about the speakers and their drivers could be profiled at the factory and loaded into the memory of a custom STR preamp that has three sets of balanced outputs corresponding to the Highs, Mids and Lows. Mate it all to amplifiers of your choice (or 3 STR amps if you like), set it up in your room and run ARC. You now have a complete, turnkey audio solution that should be as transparent and linear as one could hope to assemble. Just don’t forget the HDMI next time! 😉
I would like to thank my colleagues Dr. David A. Rich and Robert Kozel for their invaluable assistance in this review.