Anthem STR Integrated Amplifier-DAC Review
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Anthem STR Integrated Amplifier-DAC Review
Written by Roger Kanno
Anthem began as a line of less-expensive audio electronics made by Canadian manufacturer Sonic Frontiers, which in the 1990s was known for its tubed components. In 1998, Sonic Frontiers was acquired by loudspeaker manufacturer Paradigm, and in the years since has built a strong reputation primarily based on their solid-state power amplifiers and their AVM and D series of audio/video processors, and eventually the Sonic Frontiers name was replaced with Anthem. While there have been a few Anthem stereo components over the years – e.g., the budget-oriented TLP preamplifier, Integrated 225 integrated amplifier, the formidable P2 power amplifier (still in production), and, of course, their original tubed components, I would say that Anthem has never been considered much of a player in the high-end stereo market.
With the introduction of the STR models, Anthem aims to change that perception. The first STR model is the subject of this review: the full-featured STR Integrated Amplifier ($4499 USD), now followed by the STR Preamplifier ($3999) and STR Power Amplifier ($5999). While priced high in comparison to other Anthem models, the STRs are at the low end of prices in high-end audio, and so still are in keeping with Anthem’s original spirit of providing high value for lowish cost.
A very integrated amplifier
Why would a company best known for its multichannel products build a line of relatively high-end two-channel components? Perhaps because they can. With a group of talented designers based at the Paradigm Advanced Research Center (PARC), in Ottawa, Canada, such past Anthem products as the D-series preamplifier-processors and the P and M series of power amps set new standards for value and performance at very reasonable prices. The PARC team also developed the highly acclaimed Anthem Room Correction (ARC) software now used in all Anthem pre-pros, in Paradigm subwoofers, some Paradigm wireless products, and – now that MartinLogan is owned by the same private-equity firm that owns Paradigm and Anthem – in some MartinLogan speakers and subs.
With all of this design expertise, R&D resources, and advanced manufacturing available to Anthem, I’m a little surprised that it’s taken them this long to develop a sophisticated stereo product like the STR Integrated. Backed by a five-year warranty, and measuring 17”W x 6.75”H x 17.5”D and weighing 40 pounds, this large integrated amp definitely looks and feels the part of a sophisticated stereo product. Considering all the technology packed into the STR Integrated, $4499 for a high-powered integrated amplifier in 2018 doesn’t sound like all that much.
The STR Integrated has eight bipolar output devices per channel and a massive, custom-designed toroidal transformer. Anthem specifies the amp as delivering continuous power outputs of 200Wpc into 8 ohms, 400Wpc into 4 ohms, or 550W into 2 ohms. It has a high-quality built-in DAC, as well as an asynchronous sample-rate converter (ASRC) that upsamples all input signals to 32-bit/192kHz. The S/PDIF inputs support signals up to 24/192, and the asynchronous USB input up to 32/384 PCM and DSD 5.6MHz. There’s also a high-quality moving-magnet/moving-coil phono stage. That’s quite a collection of features, and at this point most manufacturers would likely call it a day. But Anthem also includes ARC, as well as sophisticated bass management for mono or stereo subwoofers – features rarely found in two-channel integrateds.
Highlights of the STR’s feature set include four speaker profiles, in which the user can specify whether or not the system includes subwoofers, and if so, how many, and whether they are to operate in mono or in stereo. Bass management can be set independently for each profile, including the crossover frequency (25-125Hz in 5Hz increments), and phase and polarity, the latter adjustable in 5-degree increments for each sub. The distance from the listening position to each speaker or sub can also be set individually, from 0’ to 29.5’ in 2” increments (or from 0 to 9m in 5cm increments). Finally, the output level of each speaker and sub can be adjusted in 0.5dB increments through a range of -12.0 to 12.0dB.
Considering all its features and configuration options, the STR Integrated has more in common with a pre-pro or AVR than with most integrateds. Thankfully, Anthem has provided an extensive menu system, visible on a large, dimmable color display that’s easy to read and to use. Up to 30 virtual inputs can be separately named, specified, and assigned to any physical input, and the display will then show the selected input, data type, and sampling frequency, and whether ARC is engaged. One cool feature: When you cycle through the inputs, the display momentarily shows not only the selected input’s name, but a large image of the type of connector used for that input – it makes identification easier. The Thin Film Transistor (TFT) display can be set to show only the volume level, displayed in large characters that can be easily read from across the room.
Too many other settings are included to list them all; a few examples are analog input levels, mute levels, and display brightness. Although, by default, all analog input signals are converted to 32/192 digital, they can also be set to Analog Direct, which bypasses digital conversion and defeats any digital signal processing (DSP), such as ARC and bass management. An updated version of the STR Integrated’s firmware, released in March 2018, adds a home-theater bypass option that lets the user set any analog input to unity gain. This will pass along the incoming left and right stereo channels only to the preamp outputs, not to the subwoofer(s); any connected subwoofers will thus not be active when the STR is in home-theater bypass mode.
Speaking of inputs and outputs, the STR Integrated has four analog stereo inputs (RCA), one pair of balanced inputs (XLR), and separate MM and MC phono inputs. Digital audio inputs comprise two TosLink, two coaxial RCA, one AES/EBU, and a USB Type-B. There are also an RS-232 connection, a 12V trigger output, an Ethernet jack, an IR input, a USB Mini-B port for firmware updates or to set up ARC directly from a PC, and a USB Type-A port for factory use. RCA analog outputs consist of a fixed-level pair, and variable line-level outputs for two subwoofers and the left and right preamp outputs. The speaker terminals are large, five-way binding posts, and there’s a standard IEC power inlet for the supplied power cord. In the right half of the front panel is a row of five small buttons: three for navigating the menu system, plus Mute and Power buttons. Toward the center of this row is a much larger volume/selection knob whose action has a solid, weighty feel. This half of the front panel is gently convex, which adds a touch of elegance. The available finishes are black and a highly attractive silver; I preferred the latter. The remote control is relatively small, with a top panel of black, brushed aluminum, and plastic buttons that click when pressed.
For the last ten years my reference stereo preamplifier has been an Anthem D2 with Anthem Room Correction (ARC) – I’ve found this highly user-configurable software to be an effective way of fixing room anomalies in multichannel and stereo systems. The STR Integrated includes the same high-quality, calibrated microphone, but uses the new version of the software, ARC-2, and a new articulated mike stand that can be angled in several directions. To use ARC-2, the STR Integrated must be connected to your home network via Ethernet, or directly to a personal computer via USB. ARC-2 allows those who don’t want to use a PC to run the software through an iOS app, using either Anthem’s calibrated mike or the iOS device’s built-in mike.
The STR Integrated’s phono stage includes a rumble filter that can be set from 10 to 60Hz in increments of 1Hz. There are also multiple non-RIAA filters and a custom equalization option. The listening mode can be set to Stereo, Mono, Both-Left, or Both-Right. However, I couldn’t explore any of this – I don’t own a turntable.
System and setup
First, I connected the STR Integrated to my home network via Ethernet, then downloaded the Windows audio driver and the latest version of Anthem Room Correction, ARC-2, with unique calibration file (you’re asked to enter the microphone’s serial number). I then ran ARC-2 to set up multiple speaker profiles for the Paradigm Persona B speakers, used with and without two JL Audio E-Sub e112 subwoofers, and a third profile for my MartinLogan Masterpiece Classic ESL 9 speakers. The process was quick and easy; I was up and running in minutes.
I connected the STR Integrated to my laptop with an AudioQuest Carbon USB cable and JitterBug USB Data and Power Noise Filter, and played music via foobar2000 and Roon. Speaker cables were Analysis Plus Silver Apex, and power cords and power conditioning were my usual assortment of products from Blue Circle, ESP, and ZeroSurge.
Class-AB meets DSP
The Anthem STR Integrated Amplifier sounded damn good right out of the box, but even better after ARC-2 had done its stuff. Unless you have a really good-sounding room to start with and are meticulous in setup, not to use ARC is not to use the STR Integrated to its full potential. Whether with the MartinLogan Masterpiece Classic ESL 9s or the Persona Bs with two subwoofers, activating ARC-2 allowed the STR to play at any volume level, from very low to extremely high, with absolute composure and coherence throughout the entire audioband. I could sit back and listen to Lorde’s Melodrama (16-bit/44.1kHz FLAC, Universal) at moderately low levels and let her ironic lyrics flow effortlessly around me. Even at these levels, “Green Light” had a solid beat, and I could hear her every vocal inflection, even when overlaid by a chorus of backing singers. The drums and lower registers of the piano had tons of weight through the nearly-full-range ESL 9s – I never felt the need to crank up the volume, so complete was the STR Integrated’s control over the speakers.
The ultra-deep, undulating bass of “Solar Sailer,” from Daft Punk’s music for the film Tron: Legacy (16/44.1 FLAC, Walt Disney), relentlessly pounded my room through the STR Integrated – but I was more impressed by the Anthem’s composure with “The Game Has Changed,” which has some scary-loud drumming interspersed with buzzing electronic tones that simply refused to distort, even at insanely high volume levels. With the ML Classic ESL 9s and the STR Integrated, the drum whacks were startlingly loud, yet started and stopped with extreme precision, and remained in perfect balance with the rest of the music. I sat amazed at how well integrated the sound was, even at these extreme volume levels.
I switched to “Homesick,” from Dua Lipa’s Dua Lipa: Deluxe (16/44.1 FLAC, Warner Bros.). The piano was more forward in the mix than the piano in Lorde’s “Green Light,” but it had a beautifully resonant quality that provided a great sense of depth, and the purity of the vocals was exquisite. Through the STR Integrated, the sound of her heartfelt singing was exquisitely blended with Chris Martin’s backing vocal, with touches of sweetness and liquidity that I didn’t expect to hear from such a powerful solid-state amplifier.
The authority the STR Integrated with ARC-2 exerted over the ML Classic ESL 9s’ four 8” woofers and two electrostatic panels was beyond reproach, but the Anthem also extracted fulsome amounts of bass from my Paradigm Persona B bookshelf speakers without sounding the least bit bloated. Where the STR Integrated also shone was in its ability to integrate the outputs of my subs with that of the Persona Bs, combining the bookshelfs’ crystal-clear midrange and highs with the JL Audio E-Sub e112s’ super-deep yet agile bass. The drums in Daft Punk’s “The Game Has Changed” now hit harder and faster than with the MartinLogans, with more clarity in the orchestration and greater soundstage depth. The Persona Bs and JLA subs didn’t throw quite as wide a soundstage as the ML Classic ESL 9s, but the deeper reach of the dual subs and the STR Integrated’s ability to merge the outputs of all four speakers into a completely coherent, full-range soundfield resulted in the best sub-sat sound I’ve heard in my room. Whether with full-range floorstanders, bookshelf speakers, or bookshelfs with subwoofers, the advanced DSP functionality of the STR Integrated proved an invaluable feature.
I then compared the STR Integrated with my reference amplification: an Anthem D2 pre-pro ($7500 when available) that also includes ARC, and a pair of Anthem M1 power amplifiers ($7000/pair). The STR Integrated provided nearly the same sound quality and increased functionality, at least with stereo sources. ARC-2 runs more quickly and has more configuration possibilities than does ARC, the version running on my D2, including permitting multiple profiles with different speaker arrangements. That might not be of much use to the average user, but this reviewer appreciated the ability to have multiple speaker profiles that I could easily switch between to run comparisons. One limitation of the STR Integrated is its inability to pass subwoofer signals in home-theater bypass mode. If I were to permanently install an STR Integrated in my reference system, I’d have to decide whether to use the subs for only multichannel or only stereo listening. This would be a serious compromise – ideally, I prefer to use my subs for both.
The sound quality of the STR Integrated was not unlike what I’m used to from high-quality separates – not surprisingly, it sounded quite similar to my reference Anthem components. The STR Integrated did sound a bit leaner than the D2-M1s combo, but not objectionably so, and its overall sound character was what I expect from a top-flight class-AB power amp. The sound was a touch more forward with the STR Integrated, which gave such pop songs as “Every Day I Write the Book,” from Elvis Costello’s Punch the Clock (16/44.1 FLAC, Columbia/Rhino), an exciting immediacy. Sibilance was present but not exaggerated in “Beyond Belief,” from Costello’s Imperial Bedroom (16/44.1 FLAC, Columbia/Rhino) – he was positioned precisely at center stage and up front, as if he were standing in my room, the Attractions playing behind him.
The sound of the D2 and M1s was slightly more relaxed, but revealed in recordings a touch more air and detail. For instance, in “Rosanna,” from Toto’s Greatest Hits: 40 Trips Around the Sun (16/44.1 FLAC, Columbia/Legacy), there was noticeably more separation between instruments and voices even at relatively low volumes – in comparison, the STR Integrated tended to slightly homogenize the sound. The piano and drums in “Hold the Line” also seemed to emanate from roughly the same plane with the STR Integrated; the D2 and M1s presented them at slightly different depths on the soundstage.
Anthem’s STR Integrated Amplifier provides sound of amazingly high quality from a single enclosure, with sophisticated microprocessor control of all functions, including room correction, bass management, and a user-configurable phono stage. ARC-2, the latest version of the PC-based Anthem Room Correction software, is fast and easy to use, and the large, intuitive menu system and color touchscreen made the STR a pleasure to operate. I can’t overstate how impressed I was by the execution of its overall design. In my years as an audio reviewer, the STR Integrated is one of the most impressive examples of a fully fledged audio product I’ve come across.
The STR Integrated may not be able to stream music over a network or from a connected storage device, but it otherwise takes the concept of the integrated amplifier-DAC about as far as it can go. If you’re open to the idea of subjecting your system to room-correction software, including the use of bass management for subwoofers, I can think of no better way to achieve reference-quality sound than by buying an STR Integrated Amplifier. Although it wasn’t quite the equal of my costlier Anthem separates, in the time the STR Integrated spent in my reference system, its performance never left me wanting more. I can’t recommend this unique product highly enough.
. . . Roger Kanno
Speakers – MartinLogan Masterpiece Classic ESL 9, Paradigm Persona B, JL Audio E-Sub e112 subwoofers (2)
Amplifiers – Anthem M1 monoblocks
A/V processor – Anthem D2
Sources – Hewlett-Packard Pavilion computer running Windows 10, foobar2000, and Roon, with AudioQuest JitterBug
USB link – AudioQuest Carbon
Speaker cables – Analysis Plus Silver Apex
Power cords – Essential Sound Products MusicCord-Pro ES
Power conditioners – Blue Circle Audio PLC Thingee FX-2 with X0e low-frequency filter module, Zero Surge 1MOD15WI