I’m in favor of using room correction and bass management in multichannel music-and home-theater systems of 5.1+ channels, as well as in 2.1- and 2.2-channel systems. I’ve also argued that anyone with a subwooferless two-channel (2.0) system who’s serious about high-quality sound reproduction should consider using room correction, at the very least in the bass region below the Schroeder frequency, which is room dependent but is typically around 300Hz.
I’ve written a number of articles on this subject for this site, such as “Integrating a Single Subwoofer into a Two-Channel System . . . for Those Unafraid to Take Measurements, Fiddle with Filters, and Apply EQ” (August 2019). I’ve written other pieces that relate to the subject of this review, the Anthem STR ($3999) -- a full-function preamplifier that includes a DAC, a phono stage, and Anthem Room Correction Genesis (aka ARC Genesis) software with built-in bass management: “Anthem’s Peter and Mark Schuck on Subwoofer Integration and Room Correction” (September 2019); “Setting Up Speakers and Subwoofers Using Anthem’s STR Preamplifier with ARC Genesis” (December 2019); and “Digitizing and Room-Correcting for Vinyl -- Taking Full Advantage of the Anthem STR Preamplifier’s Phono Stage” (January 2020). The last two articles are referred to several times below, to reduce the word count of this one -- the STR preamplifier is so complex that covering everything it does in one place would result in the War and Peace of audio reviews.
The Anthem STR preamplifier is a well-built component measuring 17”W x 3.9”H x 14.8”D and weighing 16.8 pounds. It’s available in silver, or the black of my review sample. Anthem proudly proclaims that their components are “Crafted in Canada.” For those suspicious of such claims, I can attest to the fact that Anthem’s STR product series is indeed designed, built, assembled, and repaired in Canada. Anthem, like MartinLogan, is part of the Paradigm Electronics group of companies; I recently visited Paradigm’s headquarters, in Mississauga, Ontario, and was awed by the size of the operation. Aside from integrated circuits, resistors, nuts and bolts, etc., almost everything that goes into the three brands’ speakers and electronics is designed and manufactured in-house.
The STR preamplifier’s case of thick, lightly textured metal has rounded corners, flush-mounted screws, and “anthem” stamped into the front of its top panel. The thick metal front panel is of elegantly simple design: To the left is a large screen that displays the volume level (default); or the volume level and selected input, ARC status, the input type (analog or digital) and sample rate (if digital), and whether the selected output is configured as Stereo, Mono, Both=Left, or Both=Right. The last two settings are for using a stereo phono cartridge to play a mono record with a groove whose one side is in better shape than the other -- the left- or right-channel signal can be sent through both speakers. To the right of the screen is a Menu/Select button, for navigating the STR’s menu. A large Volume knob on the right half of the faceplate is flanked on both sides by the Prev and Next buttons, for cycling through the inputs. Despite the STR’s heavy reliance on digital processing (see below), its volume control, while digitally controlled, operates in the analog domain in increments of 0.5dB from -96.0 to +7.0. At far right are the Mute button and the backlit Power button. Conspicuously missing is a headphone jack.
On the rear panel are high-quality, gold-plated connectors: four pairs of single-ended (RCA) analog inputs, two pairs of balanced (XLR) analog inputs, moving-magnet and moving-coil phono inputs, four S/PDIF digital inputs (two RCA coaxial, two TosLink optical), one USB DAC input, and one AES/EBU (XLR) digital input.
The STR’s built-in DAC, based on an AKM chipset, supports resolutions up to 32/384 PCM and DSD 2.8/5.6MHz sources via USB. The other inputs support up to 24/192 PCM.
The MC input’s impedance is specified as 100 ohms, the MM’s as 47k ohms/270pF. Unlike some other phono preamps near this price range, these parameters are fixed, and not user adjustable via the menu or DIP switches. The phono-preamp gains are specified as 61dB (MC) and 41dB (MM). While no gain is specified for the line-level preamp section, I measured 12.6dB at the unbalanced outputs and 18.6dB at the balanced, both with the volume control wide open.
As for outputs, the STR offers pairs of balanced (XLR) and unbalanced (RCA) preamplifier outputs; one pair of fixed, line-level, single-ended outputs (RCA) preceding the volume control; and two subwoofer outputs, one set on RCA and one set on XLR. There are also control and update ports: Ethernet, USB Type-A, mini USB Type-B (to connect to a PC while using ARC Genesis), infrared (IR), 12V trigger, and an RS232 port. But while the STR has balanced inputs and outputs, the preamp’s internal circuitry is single-ended.
The STR can digitize any analog input at a resolution of 32-bit/192kHz, for bass management and/or room correction via digital signal processing (DSP) operating at 64-bit precision -- a feature called Convert Analog. As you’ll read below, I found benefit in applying room correction and bass management for vinyl sources. In Analog-Direct mode, analog signals are never digitized but are passed through the STR intact; in Analog-DSP mode, Convert Analog is enabled. In Analog-Direct mode, the specified signal/noise ratios are 92dB for the MC input, 110dB for the MM input, and 120dB for the other analog inputs. With the digital section engaged, the S/Ns are 84dB MC, 102dB MM, 108dB for the other analog inputs, and 113dB for the digital inputs. All of the STR’s percentages of total harmonic distortion plus noise (THD+N) are vanishingly low, the decimal point followed by two zeros, with one exception: 0.02% for the MC phono stage with Convert Analog enabled. All THD+N figures are below the threshold of audibility.
The STR also offers a unique home-theater-bypass function for its analog inputs. These inputs can be configured to be directly connected to the outputs (including the subwoofer outputs) via relays, to allow signals to be passed through the STR when the preamp is in standby mode (i.e., off). This makes possible not only a seamless blend of a two-channel system and a multichannel system, but also gives you the option of using the same subwoofer(s) in both systems. No other preamplifier I’ve seen has this set of features.
The supplied remote-control handset is small but sturdy and attractive, with a black-anodized aluminum body. It has few buttons: Volume; Mute; Balance; Power/Standby; Setup; four navigation arrows and Select; Mode, for cycling through Stereo, Mono, Both=Left, Both=Right; Info, to toggle the screen between displaying only the volume level and the other info described above; and Input, to cycle through inputs. There are also three buttons for which Convert Analog must be engaged: Levels, for adjusting the output level(s) of attached subwoofer(s); and the Bass and Treble tone controls.
System setups -- external and internal bass management
I incorporated the STR preamplifier into my reference system using two different configurations. The first reflects my current setup using external bass management. I connected the STR’s balanced outputs to my left and right SVS SB-4000 subwoofers, each of which sits a third of the distance from one sidewall and between the left and right main speakers, the subs’ low-pass filters (LPFs) set to 130Hz, 24dB/octave. The subs’ balanced outputs fed the inputs of a Marchand Electronics XM446XLR-A -- a passive, line-level, high-pass filter (HPF) set to 120Hz at 24dB/octave. The Marchand’s outputs fed the balanced inputs of my McIntosh Laboratory MC302 power amplifier, whose 8-ohm taps drove Focal Sopra No1 speakers (I recently reviewed these for SoundStage! Hi-Fi).
I used a second setup to test the bass management of the ARC Genesis software, which is built into the STR. I removed the Marchand HPF, connected the STR’s balanced subwoofer outs to the SVS subs, and the balanced main preamplifier outputs directly to the balanced inputs of my MC302. All other connections remained unchanged from the first setup.
For both setups, the speakers were 16” from the front wall, toed in 18°, and described a 9’ equilateral triangle with my listening chair.
For sources, I connected a Surface Pro 6 running Windows 10 to the STR’s USB input, and my miniDSP DDRC-22D processor -- its built-in Dirac Live 2.0 room correction turned on or off, depending on what I was comparing -- to one of the STR’s coaxial digital inputs. Feeding the DDRC-22D via TosLink was a Bluesound Node streamer serving as a Roon endpoint, controlled by a Windows 10 laptop dedicated as a Roon Core (v.1.7), to serve up tunes from Tidal or CDs ripped to my NAS. Analog sources included a Pro-Ject Debut Carbon Esprit turntable with Ortofon Red MM cartridge connected to the STR’s MM input, and the balanced outputs of my Rotel RDC-991 CD player. For comparison purposes, I also connected the fixed RCA line-level outputs of my McIntosh C47 preamp to the STR’s RCA inputs.
RCA interconnects were from AmazonBasics, XLR interconnects from Monoprice; my homemade speaker cables have conductors of 12-gauge, oxygen-free copper soldered to locking, gold-plated banana plugs.
ARC Genesis setup
The STR preamplifier comes with a calibrated microphone -- all you need do is download to a computer the software to run the ARC Genesis setup procedure. As explained in my December 2019 feature, I found the process of setting up ARC Genesis on my PC fairly straightforward. Using the Professional Mode, I performed nine measurements each for both the external and internal bass-management setups. For the internal, I applied ARC’s new bass-phase-alignment feature, which optimizes the phase relationships between the subwoofer(s) and speakers. I also forced the crossover point to 125Hz (ARC will automatically choose a crossover point that the user can change). I then applied the same target curve to the internal and external profiles (which I named Int and Ext), tweaking ARC’s default curve to apply 6dB of bass boost relative to 1kHz, and a gentle downslope of 1dB from 2 to 16kHz. The resulting curve, as seen below, essentially follows what Harman International’s research has shown to be the loudspeaker curve preferred by most listeners. I also saved a third profile, based on the measurements taken with external bass management, for which I switched off the EQ above 350Hz. This profile, which I named Bass Only, corrected my room’s bass anomalies while preserving the Sopra No1s’ natural boost in the presence region of the midrange (400Hz-1kHz). As I discuss below, ARC Genesis gives the user control over the target curve in the bass and treble regions, but not through the midrange specifically.
While I would love to explain every feature found in the many layers of the STR’s menu, I fear doing so would cause undue pain to even the most dedicated reader. Instead, I’ll describe what I think are the most important things that are unrelated to sound quality.
As I mentioned in my January feature about the STR preamplifier’s phono stage, Anthem offers an unprecedented level of flexibility in assigning inputs. Although there are 12 physical inputs -- six line-level analog, two phono, and four digital -- the STR lets you create up to 30 “virtual” inputs, each assignable to a physical input, and each with an associated profile that describes its configuration, with too many options to list here. Because the maximum number of virtual inputs exceeds the number of physical inputs, it’s possible to assign multiple virtual inputs to one physical input. For my turntable, for example, I assigned two virtual inputs: one purely analog, the other digitized.
The STR also offers gain trim of ±20dB, in increments of 0.5dB. This applies only to the physical analog input jacks, but it’s convenient for matching the output levels of source components.
When I review a preamp with as many features as the Anthem STR, I like to test every input to ensure that all work as they should. My review sample’s RCA and XLR line-level analog inputs functioned without a hitch, as did its Phono MM input (I had no MC cartridge with which to test the Phono MC input). On the digital side, the coaxial and optical inputs both accepted signal resolutions of up to 24/192 PCM, and the USB input accepted up to 32/384 PCM. I also successfully ran a DSD64 file through the USB input, the STR’s screen announcing “DSD 2.8MHz.”
I plumbed the depths of the STR’s noise floor. With an unused analog input in Analog-Direct mode and the volume control wide open, it was very quiet -- I could hear a bit of hiss above the self-noise of my extremely quiet McIntosh MC302 amp, but only with an ear placed next to a tweeter. With Convert Analog enabled, however, I could hear the STR’s noise from my listening chair, and could just barely hear it with any digital input selected, and with or without ARC engaged. Though the STR’s noise floor was respectably low in all circumstances -- well below the threshold of audibility with music playing -- this was still a bit disappointing for a $3999 preamp. A senior Anthem engineer suggested one possible reason for the noise. He informed me that the STR’s digital section has an extra 12dB of gain, in order to provide a very high output voltage for low-sensitivity amplifiers. Higher gain usually means more noise.
The following observations will likely be of interest only to those who regularly use the front-panel volume control. The STR’s volume increments of 0.5dB made possible fine enough adjustments, but I had some problems with the knob itself. I like to set up preamps right next to my listening chair so I can adjust the volume with one finger, but the STR’s knob doesn’t stand proud of the faceplate quite far enough for one finger to comfortably rest on it. Also, the knob isn’t knurled -- it wasn’t easy to turn the knob without my finger slipping off. A very minor quibble.
Sound -- without ARC Genesis
I spent several months with the Anthem STR in my two-channel system, and with the exception of its phono stage, not once did I hear any sonic fingerprint with ARC Genesis disabled. I exercised due diligence and performed time-synchronized comparisons of the STR with my McIntosh C47 preamplifier-DAC ($4000), their output levels matched to within 0.2dB. My reference tracks were: “Find My Home,” from Colin James’s Rooftops and Satellites (16-bit/44.1kHz FLAC, True North); “Give Me One Reason,” from Tracy Chapman’s New Beginning (16/44.1 FLAC, Elektra); the title track of Don Henley’s The End of the Innocence (24/48 FLAC unfolded to 24/96 MQA, Geffen/Tidal); and “The Last Resort,” from the Eagles’ Hell Freezes Over (16/44.1 FLAC, Geffen). The C47 sounds as neutral and detailed as any preamp I’ve heard, and with each track, as I switched between it and the STR, there was never any change in the sound. The conclusion was unavoidable: as a line-level DAC and/or preamp, the STR’s sound was as transparent as the C47’s.
As I mentioned in my January article, the STR’s MM phono preamp was also quiet. While digitizing the analog phono signal did raise the noise floor, in my comparisons of the STR’s pure and digitized analog sounds I preferred its digitization of my Ortofon Red’s output, even without ARC room correction -- it seemed to sharpen the imaging and transients, if at the expense of a slight loss of smoothness, which some might actually prefer.
To keep my comparisons of the STR’s and C47’s phono stages entirely within the analog domain, I set the Anthem’s Phono MM input to Analog-Direct mode, and matched the levels by ear. (I don’t have an LP with test tones.) Both preamps were very quiet, with noise floors far below the surface noise of every LP I played. My first impression, after listening to a few records through both phono stages, was that there were no obvious differences. Only after going back and forth several times did some differences emerge. “Anna Begins,” from Counting Crows’ August and Everything After (2 45rpm LPs, Geffen/Analogue Productions APP 24528-45), begins with well-recorded unaccompanied drums and hi-hat just slightly right of center, after which an acoustic guitar enters on the left. With both preamps, the dynamics and clarity were first-rate, delivering the impacts of plucked guitar and sticks on skins with snap and speed, while preserving gentle nuances of decays and room reverberation. However -- when I focused on the bass from the kick drum, the C47 seemed slightly more incisive, giving me a bit more punch and speed; and at the other end of the audioband, the STR seemed to provide a little more extension and shimmer. With the Anthem, for example, the opening cymbal stroke seemed to spread out a little farther in space, and took longer to die away. The hi-hat that follows also seemed to shimmer and shine a bit more through the STR, which also offered just a little more energy and delicacy in the top end -- all of which I found pleasing.
When I focused on Adam Duritz’s voice, I was again pleased with the sounds of both preamps -- it had body and presence, its image tightly and cleanly placed at center stage, just above the plane described by the speakers’ top panels. All details of his singing -- his inflections and tonal shifts -- were preserved through both phono stages. I heard a hair more sibilance through the STR, but not to the point of its being distracting or exaggerated. Once I’d heard these differences, I found them easier to pick up when I then listened to Blue Rodeo’s Five Days in July (LP, Warner Bros. 1-143146).
I can’t see how any casual or even semi-serious vinyl enthusiast would be anything but completely satisfied with either phono stage.
Sound -- with ARC Genesis
As I explained in my December article, enabling ARC Genesis in the Anthem STR improved the sound of my system. In that piece I discussed how tweaks to ARC’s default target curve cured my then reference speakers, Bowers &Wilkins 705 S2 minimonitors, of their hot treble, and my room of its uneven bass response. I had similar results when I applied the same ARC Genesis target curve to the combo of Focal Sopra No1s and SVS SB-4000 subwoofers. I find the Sopra’s treble response just about perfect, but with recordings that lean toward a bright sound or display excessive sibilance, in my room the Sopras can benefit from up to 1.5dB of trim between 2 and 16kHz. With ARC’s Tilt Level and Tilt Start Frequency controls, I was able to dial in the Focals’ treble to perfection. With “Turn Me On,” from Norah Jones’s Come Away With Me (16/44.1 FLAC, Blue Note), this recording’s overemphasis of her sibilants was decreased enough with ARC activated to produce a more pleasing listening experience.
In December I also explained how the STR had produced no improvements in imaging and soundstaging with ARC on or off, and this also applied to the Focal-SVS combo. However, this was more a function of the near-perfect left/right symmetry of my acoustically treated listening room than it is a comment on ARC’s efficacy -- the software evidently knew well enough to let my system’s already superb imaging alone.
Because bass-response anomalies are a function of the room and the speakers’ positions within that room, I experienced exactly the same improvements with ARC Genesis engaged with both combos: 705 S2 with SB-4000s and Sopra No1 with SB-4000s. ARC Genesis evened out the bass response and filled in the 60Hz null, as shown in the ARC Genesis plot above, and I could really feel the difference in impact and slam when playing kick drums at loud levels.
After matching the levels of the STR using a 31.5Hz test tone, I compared my ARC Ext profile (external bass management by Marchand HPF and SB-4000 LPF) with my ARC Int profile (internal bass management by the STR’s DSP crossovers) by playing some of my go-to bass tracks: “You Shook Me All Night Long,” from AC/DC’s Back in Black (16/44.1 FLAC, Atco); “Hotel California,” from the Eagles’ Hell Freezes Over (16/44.1 FLAC, Geffen); “She Will,” from Lil Wayne’s Tha Carter IV (16/44.1 FLAC, Cash Money); and “Birds,” from Dominic Fils-Aimé’s Nameless (24/44.1 FLAC unfolded to 24/88.2 MQA, Ensoul/Tidal). I heard no differences between the two setups -- ARC Genesis was replicating the bass management I’d built up using my SVS subs’ crossovers and the Marchand HPF. In one word, this was convenient. I wish I’d known about the Anthem STR before doing all that work!
ARC Genesis vs. Dirac Live
I use Dirac Live 2.0 room correction installed in a miniDSP DDRC-22D. But with the arrival of the Anthem STR preamp with built-in ARC Genesis, I was at last able to compare the efficacy of these competing room-correction softwares. Each provides tremendous if differing benefits, along with some deficiencies.
As I mentioned in my December and January articles, ARC Genesis allows you to adjust the target curve in the bass and treble, but not specifically in the midrange -- if you want to leave your speaker’s midrange performance untouched, the only option is to turn off the EQ function above the Schroeder frequency. But Dirac Live 2.0 gives you full control of the target curve throughout the audioband. This means that, in Dirac Live, I was able to leave the Focal Sopra No1s’ natural rise in the midrange effectively unaffected, while still applying the broadband 1.5dB reduction through the treble that I desired. The Dirac Live 2.0 plot below shows the in-room response of the left Sopra No1 and SB-4000 subwoofer, averaged over the same nine microphone positions used for the ARC calibration.
In direct comparisons with the ARC Genesis Ext curve I’d created, which removes the Focals’ midrange bump, my Dirac Live curve, which preserves the bump, resulted in the Sopra No1s’ midrange sounding livelier, more present, with more body -- voices leapt from the mix, as they do when I listen to the Focals with no room EQ. I prefer this type of lively midrange; those who like a more neutral sound may prefer what ARC Genesis did. What’s better is up to you -- and your speakers.
Next, I performed an apples-with-apples comparison of Dirac Live 2.0 and ARC Genesis to see if, using the same target curves, I could hear a difference, as the two systems implement their filters differently. I created a Dirac Live target curve that matched as closely as possible the target curve I used with ARC Genesis. The plot below shows this target curve superimposed on the in-room response of the left Sopra No1 and SB-4000.
I matched the levels to within 0.3dB at 2kHz (-0.3dB for the STR) and 0.2dB at 31.5Hz (+0.2dB for the STR) and compared several tracks, including Colin James’s “Find My Home,” Dominic Fils-Aimé’s “Birds,” and Tracy Chapman’s “Give Me One Reason.” I heard almost no difference: soundstaging, imaging, midrange transparency, detail, presence, treble extension, and dynamics were all identical through both systems, but I did hear very slightly more bass output with the STR and ARC Genesis -- it sounded a little more powerful -- but no difference in bass tautness, control, or cleanness. That difference was probably more a result of my inability to perfectly match the shapes of the two target curves in the bass. Because both Dirac Live 2.0 and ARC Genesis offer the user full control of the target curve’s bass region, and I have two subwoofers, I can have as much or as little bass as I want.
While either room-EQ software will improve a system’s sound, Dirac Live 2.0’s lack of bass management makes it lose points to ARC Genesis. Dirac Live 2.0 also lacks its own hardware solution -- instead, it relies on partnerships with other manufacturers, such as NAD and miniDSP, who may or may not offer their own bass-management systems. (NAD does offer bass management in their C 658 preamp-DAC and Masters Series M33 integrated-DAC, as does miniDSP in their SHD preamp-DAC-processor-streamer, but I haven’t used any of these. Dirac Live recently announced its own bass-management feature, which should soon be available as an add-on to partnering products, but I haven’t seen that either.)
But ARC Genesis handles all bass management for you, and it’s built into the Anthem STR preamp. The STR also offers discrete bass management for two subwoofers, which is rare, if not unique, among two-channel preamps. Those features make the STR a one-stop shop for those who want to assemble a high-performance two-channel system with one or two subwoofers and full room correction.
When, in March 2019, I reviewed the Simaudio Moon 390 preamplifier-DAC for SoundStage! Hi-Fi, I was impressed by its versatility and endless array of inputs and outputs. But I wondered if I could ask for even more: a preamp that does truly everything. Such a preamp would add integrated room correction, and configurable, line-level, single-ended and balanced subwoofer outputs. Anthem’s STR preamplifier provides these features but still doesn’t do it all -- it lacks the Moon 390’s headphone amp, HDMI inputs/output, and built-in network streamer. It would seem that, for now, two-channel audiophiles still can’t have a preamp with the build and sound quality they demand and with all possible features.
But the STR preamplifier comes awfully close. What Anthem has created is extraordinary for the price -- a full-featured, transparent-sounding preamplifier-DAC with all the analog and digital inputs and outputs most users could ever need (save for HDMI and a headphone jack), and exceptional input-assignment flexibility. Most useful of all, it includes ARC Genesis room-correction software, which not only helps you optimize the sound to your room, but also includes the most versatile and useful bass-management system I’ve seen for a high-end two-channel system. If you have or are planning to acquire a top-quality 2.1- or 2.2-channel system, you must consider the Anthem STR. It’s a steal.
. . . Diego Estan
- Speakers -- Bowers & Wilkins 705 S2, Focal Sopra No1
- Subwoofers -- SVS SB-4000 (2)
- Power amplifier -- McIntosh Laboratory MC302
- Crossover -- Marchand Electronics XM446XLR-A (between preamp and amp)
- Preamplifier-DAC -- McIntosh Laboratory C47
- Room-correction EQ -- miniDSP DDRC-22D with Dirac Live 2.0 (between digital sources and DAC)
- Digital sources -- Bluesound Node streamer, Rotel RCD-991 CD player, laptop computer running Windows 10, Roon
- Analog source -- Pro-Ject Debut Carbon Esprit turntable with Ortofon 2M Red cartridge
- Speaker cables -- homemade, with conductors of 12AWG oxygen-free copper and locking banana plugs
- Analog interconnects -- AmazonBasics (unbalanced, RCA), Monoprice Premier (balanced, XLR)
- Digital link -- AmazonBasics (optical, TosLink)
Anthem STR Preamplifier-DAC
Price: $3999 USD.
Warranty: Five years parts and labor.
205 Annagem Boulevard
Mississauga, Ontario L5T 2V1
Phone: (905) 564-1994