Solid State Power Amp Reviews

Listening to the DPA-1Ms through the Wilson Sabrinas, without directly comparing them with any other amplifier(s), I was impressed with their clear, open sound, resolution of fine detail, dynamics, and freedom from coloration. All of these characteristics were evident in the playback of my usual test CDs, which included the Chesky Records Jazz Sampler & Audiophile Test Compact Disc, Vol.1 (CD, Chesky JD37), Reference Recordings' orchestral sampler Tutti! (RR-906CD), Harold Farberman's The All Star Percussion Ensemble (CD, Golden Strings GS CD005), Sylvia McNair's Sure Thing (CD, Philips 442 129-2), and Robert Silverman's performance of Liszt's Piano Sonata in b and other works (CD, Stereophile STPH008-2).

The DPA-1Ms were able to drive the Sabrinas to high levels with no evidence of strain. There was certainly nothing about the sound that screamed "class-D." In fact, had I been told that I was listening to a high-power class-AB amplifier—the kind that would require the help of a friend to lift it—I would have had no reason to doubt the truth of that statement. The DPA-1M's sound was fundamentally neutral, allowing recordings to be presented without editorializing in the form of emphasizing any part of the audioband; the music reproduced was left to speak for itself.

If the DPA-1M could be said to have a character, it was in the direction of being lively—a bit forward rather than laid-back or subdued. For those familiar with digital cameras, the character of the DPA-1M was like a camera's Vivid setting, which maximizes color saturation and contrast. Of course, a system's sonic character is a function of all of the components in that system, especially the speakers, and one of the strengths of the Wilson Sabrinas is their ability to produce a dramatic, big-speaker sound that is out of proportion to their size. In this, the Sabrinas and the DPA-1Ms worked synergistically—which may be why Wilson so often uses these amps to demo the Sabrinas.

This lively, vivid quality was even more evident when I played LPs. The character of my new record player—an Acoustic Signature WOW XXL turntable with TA-1000 tonearm and Soundsmith Zephyr MIMC cartridge—is in the same direction, in contrast to the softer, more laid-back sound of my previous record player, a Linn. At times—such as when playing RCA Dynagroove LPs—the combined effect of these vivid qualities of phono front-end and amplifiers was too much of a good thing. However, with something as well recorded as, say, the audiophile classic Lincoln Mayorga & Distinguished Colleagues, Volume III (LP, Sheffield Lab 10001), the tonal balance seemed just right. The DPA-1M was also highly resolving of such phono-playback tweaks as Synergistic Research's Phono Transducer, or PHT (see Follow-Up in the October issue).

Prometheus Unbound
Given that the above-mentioned Theta Digital Prometheus monoblocks were still in my home—if I had been familiar with them in time for the first round of voting, they would have gotten my nomination as Stereophile's 2015 Amplification Component of the Year—the Audio Alchemy amps were up against formidable competition. And, all things considered—including price, size, and weight—the DPA-1Ms did very well.

In broad terms, the DPA-1M was not as good as the Theta Digital Prometheus. The Prometheus had a delicacy, a fine-grained quality that was even more resolving of sonic differences than the DPA-1M. Orchestral music was reproduced with more "body" in the sound—even though, regarded on its own, the bass extension of the DPA-1M seemed perfectly fine. Highs were more delicate, and there was more air in the sound. (All comparisons were made with levels matched.) To use another photographic analogy, the DPA-1M was like a camera that uses an APS-C sensor, whereas the Prometheus was like a camera with a full-frame (35mm) sensor. Larry Greenhill, who reviewed the Prometheus in Stereophile's March 2015 issue, was right: it's a very special amplifier.

And so, in a more modest way dictated by its price, is the DPA-1M. Like the Prometheus, it produced no artifacts, and added none of the "clinical" sound for which class-D amplifiers are often criticized. Setting aside comparisons: the DPA-1M could reproduce music from CDs and LPs in a way that was faithful to that music, with no sense of anything being missing from it. It was only in direct comparison with the Theta Digital Prometheus that it became clear that a higher level of sound quality was possible.

How close?
How close was the sound quality of the Audio Alchemy DPA-1M to that of the Theta Digital Prometheus? Suppose I said something like, "The DPA-1M gives you 80% of the sound quality of the Prometheus for a third of the price." That sounds reasonable—but maybe that percentage should be 90%. Or how about if I said 84%? Now, that sounds precise, even . . . objective. However, any such statement, although appearing to be quantitative, really only gives an impression of being objective. In fact, other than citing the correct price, any such approximations of quality are purely subjective—assigning a specific number to describe the degree of difference heard is largely arbitrary. So I'm not going down that numerical road.

What I will say is that the DPA-1M is a very fine monoblock power amplifier that's truthful to the music, and whose sound quality approaches but does not reach the level available from the far more expensive Theta Digital Prometheus. If I had to choose between the two amplifiers and cost was not an issue, I would go for the Prometheus. But if the Prometheus were out of my price range, I could live quite happily with the Audio Alchemy DPA-1M, confident in the knowledge that I was getting most (80%? 84%? 90%? Oh, never mind . . . ) of the Theta's sound. Audio Alchemy is back, and it's a reason for value-conscious audiophiles to celebrate.