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Anthem STR Preamplifier and STR Power Amplifier

Anthem STR Preamplifier and STR Power Amplifier

For eight years, an Anthem Statement D2v processor has been at the heart of my audio system. Multichannel music is a priority for me and in 2011, when I purchased the D2v, there were not many other suitable products at anywhere near the Anthem’s price of $7499. Even now, the current iteration—the D2v 3D ($9499)—has few competitors, and the original pre/pro has continued to serve me dependably with both surround and two-channel sources. But time marches on. The D2v has nary a USB input and its Asahi Kasei Microdevices (AKM) DAC chip isn’t DSD capable. Although Anthem was in on the ground floor with DSP room-correction equalization to compensate for the inevitable acoustic shortcomings in domestic listening environments, I was aware the company had made substantial advances beyond the incremental updates offered to my version of the Anthem Room Correction (ARC) software. So when given the chance to get to know Anthem’s top-of-the-line STR stereo preamplifier and stereo power amplifier, no arm-twisting was needed—even if multichannel capability wasn’t part of the package.

The single most expensive part of many high-end electronic products is the chassis and the STR components will have you thinking you’ve gotten your money’s worth, the industrial design conveying an aesthetic of solidity and understated elegance. The form factor of the two components, both available in a silver or black finish, is similar. The right side of the front panel, gently convex in shape, has a few controls, while the left is dominated by a TFT (thin-film-transistor) LCD display. The amplifier’s virtual VU meters, one for each channel, are entertaining for a week or two but, probably, you’ll eventually decide to turn them off. The display on the STR preamplifier, however, is a strong selling point. From the onscreen “Preferences” menu, the user chooses between two settings, “All” or “Volume.” The former shows the gain level in the center of the display with other useful information at the four corners—the input selected, the format and sampling rate for digital sources, mono vs. stereo, and whether ARC is activated. With the latter setting, only the volume level is displayed, in three-quarters-of-an-inch-high numbers that are easy to read from across a darkened room or in broad daylight. 

The front panel of the STR preamplifier demonstrates just how far the user interface for a complex consumer electronic device has come in a decade. Multiple layers of onscreen menus to program and operate components are now, of course, standard, and the implementation of such systems is something that Anthem is really good at. My beloved D2v sports 41 buttons on its forward-facing surface; the STR pre-amp has just fiveon/off, mute, and three buttons to navigate the menus, in the event you’ve left the supplied remote control back at the listening position. 

The STR’s connectivity is comprehensive. In back are multiple RCA and XLR inputs, several of which can be configured for “home theater bypass” and two phono inputs. This bypass allows the stereo STR preamp to be used in conjunction with a multichannel amplifier in systems that do double-duty for stereo and multichannel reproduction. When this mode is enabled all digital processing is turned off. 

Anthem, as expected, provides all the digital connections you could want (almost—HDMI is MIA), upsampling to 32-bit/192kHz resolution. These include coaxial, optical, AES/EBU, and asynchronous USB, the last of which handles up to 32-bit/384kHz PCM and DSD 2.8 and 5.6MHz, courtesy of an XMOS XHRA-2HP chip. If your computer is a Windows machine, you must download an XMOS driver from Anthem’s website to use the USB interface; for Mac, it’s simply plug-and-play. 

The back panel actually gives only a modest indication of the STR preamplifier’s robust control capabilities; up to 30 virtual inputs can be programmed. Both preamp and amp will automatically turn off rather quickly, unless you tell them not to. There’s a switch on the back of the amplifier that disables the automatic shutdown, and a menu on the preamp lets the user specify that the device will cease and desist in an hour, two hours, six hours—or never. A bass-management menu allows the user to optimize LF performance with adjustments of the subwoofer crossover frequency, as well as polarity and phase.

No one will mistake the STR power amplifier for a Class D model. Weighing in at 60 pounds (it looks more massive than that), this dual-mono Class AB design is rated to deliver 400 watts per channel into an 8-ohm load, 600Wpc into 4 ohms, and 800Wpc into 2 ohms—it consumes 65 watts when idling and from 150 to 300 watts at typical playback levels. 

Inside are enormous toroidal power supplies, sixteen bipolar output transistors per channel, and a proprietary input circuit that Anthem calls “a complementary active-loaded cascoded feedback arrangement.” There are two internal heat sinks per channel. The amplifier monitors internal temperature, current, and voltage, and an “Advanced Load Monitoring” feature allows a concerned user to check on the status of things as often as that user’s psyche requires. 

The owner’s manual does advise that “bass-heavy music” played loudly could raise the temperature sufficiently to trigger automatic shutdown of the amplifier. In my room in May, the amp’s internal temperature was in the 97° to 100° range after idling overnight, increasing by about 10° with half an hour of Daft Punk and Blue Man Group. I suppose an afternoon of Steel Pulse could potentially turn the unit off—but someone else will have to undertake that experiment. (Thermal shut-down occurs at 176° F, quite a bit above the maximum operating temperature I experienced.)

Paradigm Electronics, which acquired the Anthem brand more than 20 years ago, introduced its first DSP room-correction technology in 2008. The software has evolved continuously since then, but at two junctures the product was felt to have changed enough to warrant a new designation. The first was in 2014, when ARC became ARC-2; the second was in May of 2019, with the release of ARC Genesis after a lengthy period of beta-testing. I downloaded the latest build of the new version for this review.

The new Genesis software, compatible with both Windows and Apple platforms, has a redesigned user interface that allows for non-engineering types (like me) to undertake very sophisticated EQ adjustments to address room acoustic issues. For the STR preamplifier, Anthem says that ARC now has “50% more processing power” than any earlier version of the software and that it has developed improved optimization algorithms utilizing fifteen IIR (Infinite Impulse Response) filters per channel, the processing operating at a 192kHz sampling frequency.

To implement ARC, Anthem offers three options of increasing sophistication. Easiest is to use the built-in microphone of an iOS phone equipped with ARCs mobile app; of intermediate complexity is to connect the universal microphone Anthem supplies to an iOS or Android phone or tablet running the mobile App. Note that Anthem doesn’t allow using the built-in microphone of Android phones because they’ve found that Android phones lack sufficient brand-to-brand consistency of their internal microphones’ performance.

The capability of these first two alternatives is somewhat limited—the frequency range to which equalization can be applied is restricted and you don’t get graphs to examine. Best, and surely of greatest interest to audiophiles, is the “professional” option, which requires one to install the Genesis software on a Windows PC or Mac and attach the calibrated ARC microphone (also supplied) to the computer. Provided with the STR preamplifier is a boom-style mic stand and a long USB cable to connect the microphone to the calibrating computer, which is also connected to the preamp via USB or LAN. The user specifies the loudspeaker configuration—main speakers plus zero, one, or two subwoofers—and then takes measurements of the full frequency sweeps that are sent to each speaker sequentially by the preamp from typically five, but up to ten, positions.

The instructions for installing ARC and maximizing its functionality was written by Devin Zell, Anthem’s Marketing Manager and a key participant in the beta-testing of the new software. “ARC Genesis is very user-friendly and takes the frustration out of custom-tailoring correction settings,” Zell told me, and he really seems to care that consumers see it that way. His guide provides precise directions on where to place the microphone for the five sets of calibration sweeps—surprisingly, the locations are fairly close to one another in a pattern surrounding the main listening position—and Zell has composed easy-to-follow explanations of other Genesis functions, such as how to deal with a subwoofer that has its own equalization software. Anthem is to be congratulated for having someone other than an engineer write the instructions.

As with earlier versions of ARC, the user decides how far up on the frequency spectrum to apply equalization, the default being 5kHz. Though it’s possible to do so, it’s usually not a good idea to run the software full-range because at higher frequencies the effectiveness of the correction depends on both the tweeters and microphone being at the same height as the listener’s ears. 

Once the measurements have been taken, one can tweak room gain, deep bass, crossover frequency, and several other parameters. Essentially, the user can examine the graphic representation of the room response and then massage the equalization curves to smooth out unwanted peaks and valleys. The optimization of ARC Genesis over the earlier versions was apparent: A complete five-position calibration, including the calculation and uploading steps, took just five minutes, a fraction of the time needed with the older Anthem.

Several other features of the Genesis software struck me as especially helpful. First was the “Quick Measure” function that allows one to identify major problems in a room’s acoustic signature prior to running the full ARC program. The STR preamp will generate a full-frequency sweep repeatedly from each loudspeaker and show the room’s acoustic response in real time. ARC can only boost a sagging frequency response by a maximum of 6dB without a risk of overloading the amplifier or speakers; dips in the response curve that are greater than 6dB must be dealt with initially by changing the physical location of the speakers. There’s no limit to the amount that a peak can be “tamed” by ARC.

Second, from a single set of measurements, a user can specify up to four different profiles selectable from the STR’s menu—say, corrections for a loudspeaker configuration of right, left, and subwoofer, both with and without the sub. There are circumstances where it may be advisable to actually perform more than one set of measurements, and the Genesis software allows for four. For example, in a room with a drop-down video screen, the EQ curves could look very different with the screen up or down. Finally, ARC Genesis will automatically establish a parameter I’ve always found difficult to decide on by ear—subwoofer phase. After running Genesis for a system with a subwoofer, ARC makes the call and will inform you of the optimum value in the Bass Management menu.

One bummer. Though the Genesis software is backwards compatible with Anthem, Paradigm, and MartinLogan products employing ARC-2, it won’t work with the original software on devices (such as my D2v) that connect to the host computer with an RS232 data connection. Too bad for me.

I used the STR preamp and amplifier for control, D-to-A conversion, and amplification in my system for two months. Mostly, I listened to the Anthem components as an integral pair, though I did try substituting a T+A elektroakustic DAC 8 DSD (which has multiple inputs and a volume control) for the preamp and a pair of Pass XA60.8s for the STR power amp. Digital source components were a Baetis Reference media computer with JRiver’s player for files (I installed the ARC software on that machine) and an Oppo BDP-103 universal player to read silver discs. LPs were played on a VPI Scoutmaster outfitted with a JMW Memorial tonearm and Sumiko Blue Point Evo III cartridge. On the distal end of the electronics were my usual Magico S3 Mk2 loudspeakers with Magico’s powered S-Sub employed only episodically so as not to obscure the Anthem amp’s capacities for low-end control, heft, and extension. Analog cables were mostly Transparent Gen V, and a wide variety of digital wires saw service.

Right out of their respective boxes, the STR components impressed with the immediacy, detail, and authority of their presentation with all kinds of music. First of all—and I can’t say this is a surprise, given that I’ve used the Anthem D2 for what amounts to an eternity in audiophile time—the new Genesis software works extremely well to neutralize problematic room effects. This is easy to assess, as ARC can easily be turned on and off in the preamp’s “Preferences” menu, the sonic quality transforming from good to superior with the press of a button on the remote. This was readily heard on my frequent reference for well-recorded pop/rock, Kevyn Lettau’s Songs of the Police, a JVC XRCD24 remastering of an analog original. On this disc “Every Breath You Take” is rendered as a down-tempo, gospel-inflected torch song. With ARC activated, the richly arranged backup vocals were more intelligible, and the scorching alto sax solos were less stressed-sounding at life-like volume levels. Predictably, it was the low frequencies that benefited most from DSP correction. Without equalization, the bass had something of the wooly character experienced with the jukebox at the corner bar. With ARC on, electric bass and kick drum gained considerably in clarity and slam. 

My practice over the last eight years has been to use DSP room correction only as far up on the frequency spectrum as is necessary to smooth out major anomalies seen on the room EQ curves generated by the Anthem program—the top limit being about 700Hz with the STR gear. But turning the setting considerably higher, to 5kHz (the default), to 10kHz, or even to 20kHz didn’t meaningfully compromise the transparency of the equalization process. 

Many critical listeners will conclude that the goal shouldn’t be to achieve an absolutely flat room response. In my room, there’s a rise of a few dB occurring at 5 to10kHz with the Magicos that can be largely eliminated with some knowing manipulation by ARC. But doing so resulted in a loss of “air” and excitement with a favorite orchestral selection, the opening movement of the Shostakovich Symphony No. 15 with the great Royal Concertgebouw Orchestra led by Bernard Haitink. There really aren’t many domestic living spaces that can’t be helped by well-executed DSP room correction but, obviously, you don’t want to remove the life from a recording. The baby with the bath water and all that.

I tried out the various digital inputs—all performed quite well—but gave particular attention to the USB interface, needed to support DSD codecs. What I found was that the DAC section of the STR preamplifier will not accept “native” DSD (as does the T+A DAC-8-DSD, which has a dedicated one-bit converter), but instead employs “DoP”—DSD wrapped in a PCM container—which Anthem feels involves no sonic compromise as it doesn’t involve actual format conversion. (See sidebar.) 

Are we just bearing witness to a marketing war between those brands with DACs that can handle native DSD and those that use DoP to manage DSD files? I can’t say. For what it’s worth, I preferred, by a slight margin, JRiver’s transcoding of a DSF file to 32-bit/48kHz PCM to the 2.8MHz DoP version sent over the same USB connection to the STR in terms of spaciousness and textural nuance. 

Neither option was quite as good as playing native DSD via USB from the Baetis to the T+A—there was a more lifelike gradation of dynamics and sense of occasion heard with the Shostakovich. But, honestly, these were small differences. Likewise, when it came to PCM digital transmitted via a coaxial, optical, or AES/EBU connection, the Anthem gear got startlingly close to the German DAC, which costs $450 more than the complete Anthem preamp.

Given the digital legerdemain that this preamplifier is capable of, one might be inclined to think that the phonostage was merely an afterthought. But Anthem offers six equalization curves other than RIAA as well as a user-defined curve, possibly appropriate for older records, which sounds like it is taking vinyl playback pretty seriously. Vinyl aficionados may still insist on an outboard phonostage that allows for cartridge-loading alternatives other than 47k ohms (for moving-magnet and high-output moving-coil cartridges) and 100 ohms (for low-output mc’s), and even with my modest LP playback rig I found that records sounded better when an Audio Research PH2 phono preamplifier was inserted into the chain. Most casual vinyl consumers will probably find the Anthem’s performance more than adequate. I tried sending the PH2’s output to both an upsampling digital input and to an analog pass-through alternative. The former seemed a little synthetic-sounding, so I stuck with the bypass option and did without room correction for vinyl playback.

The amplifier impressed as well when compared head-to-head with a far pricier pair of Pass XA60.8 monoblocks. Spatiality and low-end weight were excellent, and there certainly was no question of the STR running out of steam with the most dynamic recordings, like Gordon Goodwin’s Big Phat Band’s Act Your Age. With the grip that the Anthem amp applied to the Magico S3 Mk2’s woofers, I was happy to forgo the subwoofer and avoid any possibility of room overload when the big band album was played at decidedly enthusiastic levels.

Comparisons to other pieces of audio gear are one thing; comparisons to real musical experiences are another. Massed voices did quite well—the dozen singers of Stile Antico singing “Never Weather-Beaten Sail” demonstrated sibilants and final consonants that were naturally connected to the main body of the note they belonged to. The scaling of instruments of different sizes was realistic, as with violin and Steinway grand on the nonpareil 1987 Wilson Audio Specialties recording of the Brahms Violin Sonata in G major. Exactly right, as well, was the tonality of David Abel’s fiddle on that album, readily identifiable as a Guarnerius and not a Strad. And Abel is standing precisely where the late David A. Wilson said he should be: “The sonic image of the violin should originate just to the right of the inside edge of the left speaker.” And it did.

Which leads to one last observation about the STR preamplifier and amplifier combination that occurred to me as I packed them up for their next journey. 

The two components were in my system from mid-March to mid-May, which happens to be the busiest time every year for me to take in classical concerts. In that span, I saw two operas, and attended two orchestral concerts, two chamber music recitals, plus a couple of piano performances. Normally, I have a hard time listening to recordings for a period of time after enjoying the live experience, maybe for a day or so. Yes, it’s probably setting an unnecessarily high bar but I guess I’m looking for the sort of emotional connection I get from flesh-and-blood musicians in an acoustically favorable venue when I sit down in front of my audio system. I got more than a little of that when listening to canned music with Anthem’s STR electronics—it seemed that I wasn’t nearly as refractory to the appeal of my favorite recordings. That’s a distinction, for sure.

Specs & Pricing

STR Preamplifier
Type: Two-channel solid-state preamplifier with DAC
Analog inputs: Two balanced, both configurable for home-theater bypass; four RCA, two configurable for home-theater bypass
Digital inputs: Coaxial (2), optical (2), AES/EBU, USB
Phono inputs: Low-output moving-coil (100 ohm impedance, 61dB gain); high-output moving-coil/moving-magnet (47k ohms impedance, 41dB gain)
Formats supported: Asynchronous USB input: 32-bit/192kHz PCM and DSD 2.8/5.6MHz; coaxial, optical, and AES/EBU inputs up to 192kHz PCM
Outputs: Balanced right and left, two subs; RCA right and left, line-level out, two subs
Dimensions: 17″ x 4″ x 15″
Weight: 16.8 lbs.
Price: $3999 

STR Amplifier
Type: Solid-state Class AB stereo amplifier
Output power: 400Wpc into 8 ohms, 600Wpc into 4 ohms, 800Wpc into 2 ohms
Inputs: One pair RCA, one pair XLR
Input impedance: 10k ohms (RCA); 15k ohms (XLR)
Outputs: One pair of loudspeaker binding posts
Dimensions: 7″ x 17″ x 18.5″
Weight: 60 lbs.
Price: $5999

205 Annagem Blvd.
Mississauga, ON L5T 2V1

Native DSD or DoP: Does It Matter? 

The question of “native” DSD vs. DoP is a kind of religious war within a religious war. At least for some more dogmatic audiophiles, the first consideration is if DSD-encoded files sound better than PCM files of similar resolution—or vice versa. Generally, direct comparisons aren’t possible, as DSD recordings must be mixed, edited, and mastered in the PCM realm. There really is no such a thing as a “pure” DSD recording available commercially, other than analog material transferred, untouched, to DSD and the rare “direct-to-DSD” project that don’t undergo editing. But although there are well-recognized problems with DSD— quantization noise rises sharply above 25kHz and complex noise-shaping algorithms and filters are needed to assure that this phenomenon doesn’t translate into audible unpleasantness—plenty of respected recording professionals hear musically meaningful differences between PCM and DSD, especially when it comes to the low-level information that’s heard as “spaciousness,” and choose to work with the latter. Others feel they get better dynamics, more detail, and a less fatiguing listening experience with DSD.

If you are a DSD partisan, is there an advantage to listening to native DSD as opposed to the DSD-over-PCM (or DoP) variant? For both, getting a DSD file from a computer to a DAC via a USB interface requires “packetizing” of the data stream. In the case of native DSD, the stream is broken up into relatively big pieces, 8192 bits in length, which is the size of a USB packet. At the recovery end—that is, at the DAC—these chunks are reassembled into a coherent digital signal. With DoP, the DSD stream is diced into much smaller fragments of just 24 bits. With the addition of some extra non-musical bits, each packet achieves a length of 32 bits, the standard size of a data sample that the DAC can recognize as PCM content. A bunch of these 32-bit particles are then combined into 8192-bit USB packets and, ultimately, the complete data stream is reconstituted. All the non-musical packetizing bits, of course, must be removed from the DSD information.

This is where the perspective of different manufacturers can diverge. To John Bagby, a co-owner of the Anthem, Paradigm, and MartinLogan brands, the DoP process works perfectly. His succinct conclusion regarding audible differences between native DSD and DoP: “Our position is that there is no difference with a bit-for-bit copy packaged in PCM for DoP.” Obviously, those who design their DACs to receive native DSD have a different view. Lothar Wiemann, Head of Development for T+A, notes “the process for DoP is more complex with more opportunities for data loss, clocking errors, or other compromises as opposed to native DSD streaming. Further, because of the extra bits that have been added and because of the structure of the PCM format, DoP has a big data overhead and is much less efficient.”

If you are a true believer, the NativeDSD Music website offers a spreadsheet listing close to 600 DSD DACs and players, identifying which ones will accept native DSD, as opposed to “just” DoP. From my standpoint, this variable isn’t worth losing sleep over as so many other aspects of the playback system and, of course, the recording itself can trump the importance of the file format and/or the method employed to get the digital signal from player to DAC. The capacity to play native DSD should not be the overriding factor in a purchase decision regarding a preamp, processor, or DAC.

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