Digital Processor Reviews

Since its raison d'être is the ability to throughput virtually any music file at its native sampling rate, the DP-777's performance can only be gauged with a media player that itself adapts to such distinctions, preferably on the fly; thus iTunes would suit only the user who's willing to check each file ahead of time, exit iTunes altogether, manually change the file type in the Apple Audio MIDI Setup utility, then relaunch iTunes. And that is so not me. Luckily, I already own Decibel v.1.0.2, a program that plays any and every file size, natively and on the fly—and that's what I used, for the most part.

The folks at AMR were okay with that, but they recommended that I also download and try a media player called Audirvana. I've given it a whirl, and so far I'm impressed—but all of the listening impressions that follow are based on my experiences with Decibel. Given that the DP-777 itself presents so many user-selectable performance options, the addition of yet one more variable—one more unknown—was more than I could reasonably handle within the review period.

Using the DP-777's remote handset, I found it was easy to select from the various sampling rates, filters, and jitter-reduction settings on tap—or to simply trust the processor to make the best decisions for me. For the vast majority of my listening I chose the latter route, which required me to press just two buttons: Zero-Jitter Mode and AMR, the latter the DP-777's equivalent of autopilot. During use, the sampling rates, etc., of all music files (and S/PDIF sources, for that matter) were displayed on the DP-777's front panel, and all were reported accurately.

I experienced only one performance glitch during the review period: On a morning occasioned by an unusual amount of switching among different media players, the DP-777 apparently ceased to inform my computer of its presence. According to the computer's System Preferences window, it couldn't find the AMR at all. Rebooting had no effect; surprisingly enough, simply unplugging the USB cable to the AMR for a second and plugging it back in did the trick.

The DP-777 became slightly warm to the touch during normal use. Nevertheless, I kept to the manufacturer's recommendation and left the AMR powered up at all times.

Listening
Someone had put a few miles on my review sample before I received it, so I can't say how much running-in a brand-new DP-777 might require before sounding its best. I can say, however, that from Day One the AMR produced some of the least fatiguing, most involving, and altogether best-sounding digital playback I've had in my home. In much the same sense that EMT's extraordinary OFD 65 phono pickup made me wish I had twice as many 78rpm records in my collection, the AMR processor made me wish for double the number of music files on my hard drive.

The DP-777's characteristic sound was one of openness, a generous sense of scale, detail without artifice, and a barely perceptible but undeniably consistent timbral warmth. Regarding that last quality: From my listening notes, it appears that I originally reached for the word liquidity but crossed it out—probably because that descriptor is something I've come to associate with a plasticky lack of texture that I find more offensive and more tedious than almost any other shortcoming of digital sound. (That plasticky sound is something I also associate with the last very-large, very-high-tech, very-expensive digital processor of my experience.)

At times during the DP-777's stay in my home, its sound quality was nothing less than revelatory. While listening to a bog-standard CD copy of a much-loved bootleg, Procol Harum's Delicado (which found the band performing with the Los Angeles Symphony Orchestra on a good night in 1973), the clarity and the level of nuance and detail were beyond anything I'd experienced from the disc. A clarinet obbligato during the verses of "Fires Which Burnt Brightly"; the counterpoint supplied by the flutes in the final verse of "TV Caesar"; and guitarist Mick Grabham's glorious final note in the closing "Rule, Britannia" were all stunningly present. "My Little Shirtwaist Fire," from Rasputina's Thanks for the Ether (ripped from CD, Columbia CK 67504), didn't just sound more tactile: It was bigger and deeper, and the melody just plain moved, uncoiling like a spring from start to finish. And that's not to mention the texture and tone of the cellos, and the near-physicality of singer Melora Creager's exaggerated vibrato, all of which were stunning.

Orchestral music sounded especially grand through the AMR. Friedemann Layer and the Mannheim National Theaters Orchestra's live recording of Bruckner's Symphony 9 with a completion of the unfinished Finale (footnote ,1 ripped from CD, Deutschlandradio Kultur, no catalog number) was magnificent, with even more of the tension-and-release effect noted in the Rasputina track: The music moved forward humanly and, at times, unpredictably. The pleasantly brisk second theme of the first movement had far greater temporal energy through the AMR than through my reference converter, a Wavelength Proton USB DAC. Woodwinds and brass popped out of the thick orchestration in much the same manner I'm used to hearing live. String tone was luscious. And the intensity of the timpani was brilliant throughout. As my notes read: And this is digital?! Good grief!

Playback of high-resolution downloads was similarly impressive. Elton John's "First Episode at Hienton," from the HDtracks download of John's eponymous first US album, was smooth—but, again, not plasticky-smooth: There was still a good texture in the voice, strings, and Caleb Quaye's subtle, Leslie-amplified guitar, and the track maintained a human, organic feel overall. The sheer openness with which the AMR played the recent 96kHz version of George Harrison's All Things Must Pass was also impressive. Even "Run of the Mill"—the worst-sounding track on the album, for some strange reason—sounded less edgy, less congested, more open, and altogether more human through the AMR than through any other DAC at my disposal.

I did try the AMR's S/PDIF input, and was pleasantly surprised by the results. Driven from the transport of my Sony SCD-777, the DP-777 sounded distinctly warmer and more detailed than any of the Sony's filters, with greater musical nuance. The rich sound of Doc Watson's flat-picked guitar throughout the Nitty Gritty Dirt Band's Will the Circle Be Unbroken (CD, Capitol 5 35148 2) provided ample evidence of the latter, as did Dietrich Fischer-Dieskau's historic recording (with Gerald Moore) of Schubert's Die schöne Müllerin (CD, EMI 66959 2). With music of every sort, it seemed, the AMR provided more of a sense of touch, more momentum, more involvement than other converters.

What didn't it do? Although capable of sounding more substantive and forceful than through other digital sources of my experience, music through the AMR was still less so than most good vinyl (good defined as "played with an appropriately high-torque player and low-compliance pickup"), and wildly less so than shellac—although, in the latter case, I would blame the program and not the player. During the AMR's stay here, I was especially interested in hearing jazz from the late 1920s through the mid-'30s: mostly Louis Armstrong and Django Reinhardt. Digital transfers of recordings made during that time were all taken from 78rpm shellacs, of course, originals of which, in a very few instances, I'm fortunate to own. The admirably noiseless and durable CD transfers of those records are the most wretched, miserable failures imaginable when it comes to preserving and communicating the force, drama, substance, presence, and overall humanness of the originals—and the AMR could apparently do nothing to alleviate those shortcomings. (But, again, I wouldn't have expected it to: Too much of our industry's engineering community was long ago brainwashed by the small and smug notion that if something couldn't survive the trip through a Shure V-15 and a pair of Acoustic Research AR 3Axes, it wasn't worth hearing; consequently, all existing digital transfers of historic performances are scarcely worth having. Which is a damned shame.)

Conclusions
I could probably design my own loudspeaker if I had to, and I might even be able to sketch, on the cocktail napkin of your choice, a schematic for a simple tube amplifier capable of producing an audio-frequency signal (especially 60Hz). But I couldn't design a digital player or processor if my life depended on it—not even if you gave me a year to do it and a free trip to engineering school. That's just crazy.

But if I could do such a thing, all the while bearing in mind the enduring limitations of most digital recordings in circulation, it would sound like this one. For want of a better word, the Abbingdon Music Research DP-777 was friendly to literally all the digitally encoded music I played through it—friendly, but not blind to its endearing idiosyncrasies.

And while my budget doesn't allow for a $4995 digital source component, I think the AMR is reasonably priced, given both the (apparently unique) engineering on tap and what I heard.

For me, the AMR DP-777 was more than a pleasant distraction, more than just an escape from the humdrum; it provided some of the very best digital sound I've heard. Strongly recommended.

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Footnote 1: See Richard Lehnert's "Bruckner's Symphony No.9: Finally, a Finale?" in the March 2010 Stereophile, Vol.33 No.3.