PS Audio HCA-2 power amplifier Kal Rubinson Review part 3

I also played a round robin of amp comparisons that pitted the HCA-2 against the Bel Canto eVo 200.2 and eVo2, Sonic Frontiers Power 3, McCormack DNA-1 Rev.A, and the Classé CAM-350 monoblocks. Of these, the HCA-2 was most similar to the Classés, particularly in their open, grain-free, and spacious upper midrange and treble, although the HCA-2 offered a more close-up soundstage. The Classés had more generous bass at all levels, and seemingly unlimited power. At comparably high levels, the Classés inspired confidence—but while I always waited for the HCA-2 to poop out, it never did. That's important—the HCA-2 can't be bridged for more power, and, in general, biamping is not a particularly effective solution anyway.

Perhaps if I had a larger, more isolated room, less efficient speakers, or greater tolerance, I might have found the PSA's limit. The four other amps were noticeably warmer and slightly more distant in their presentations. That made them more relaxing for casual listening, even though, with slight adaptation, they were quite excellent in critical listening as well. In particular, the eVo 200.2 and McCormack seemed a little grainy and withdrawn compared to the HCA-2, but then, every amp seemed somewhat withdrawn next to the very dynamic HCA-2. The newer Bel Canto eVo2, however, offered an alternative, equally valid and convincing view of reality

Is It Just Me?
The issue of subjective evaluation is never free of the problem of adaptation. Until I see evidence better than the anecdotal reports of perceptions, many of which I have experienced, I can't but think that a large part of a component's "break-in" happens, literally, in the mind of the listener. In the course of my experience with the HCA-2, there was no real difference between my subjective descriptions of the amp before and after its long break-in, but I could perceive differences between my subjective assessments of the amp at the beginning and end of long, uninterrupted listening sessions.

At the beginning of a review period, I am attuned to the glories of the amp under test, but also to the contrast with the amp it has replaced. As the audition proceeds, the latter awareness fades and the new amp becomes completely convincing in its presentation. Switch to another good amp and the cycle repeats. So it is at those points where one amp is replaced by another that one has the best chance of determining how they might differ.

As a result, when I put the HCA-2 into my main system in place of any one of the other amps mentioned above, its tight, lean midbass seemed a huge change, but my awareness of that change quickly waned. The system became exceedingly quick and powerful with the HCA-2, capable of startling transients and an enveloping ambience that stopped short of true multichannel sound. In addition—and, perhaps, as a consequence of these characteristics—the sound was engrossing and magnetic: it was difficult not to pay attention. On the other hand, a switch back to the eVo2 seemed a more subtle change, with a slightly more distant soundstage and a bit more midbass. Resolution was just as good—on careful assessment, nothing was lacking. Continued listening, in fact, made me question even those differences that I could experience only on switch-over.

Second Guesses and Conclusions
I was scooped by ST in "Sam's Space," so I can't resist this unique opportunity to be a Monday-morning quarterback and comment on the PS Audio HCA-2's ranking, based on his comments, in Class A of "Recommended Components." There's nothing I'd like more than to point out that he missed something, got it all wrong, or that the HCA-2 is undeserving of the accolades.

But I can't. The HCA-2 will consistently impress with its speed, resolution, lack of edge or harshness, dynamic range, and—despite its size—power. Although I paired it with only a few speakers, I think it will be best when used with large, floorstanding loudspeakers of the highest resolution and low-frequency extension. It can also be used very effectively with small, stand-mounted monitors, especially if assisted by a subwoofer. Indeed, the HCA-2 even made the Celestion MP-1 minis that I use with my TV sound bigger and better than ever.

My observations support the placement of the HCA-2 in Class A. My only caveat is that, like a really good single-ended triode amplifier, it might not be an ideal partner for just any speaker or room, and therefore might be less universal in its application than some other Class A amps. You might argue that if the HCA-2's transparency reveals shortcomings elsewhere in the system and room, it is not open to criticism. However, those revelations were consistent from system to system. With the Revel Studios, I noted—and appreciated—a slight leanness in the midbass. In other setups, the same effect might not work as well.

That said, it's hard to think of another amp anywhere near the HCA-2's price that can compete with it for clarity and power. It is, like the psychiatrist's elephant in the middle of the room, impossible to ignore. If you're shopping for an amp for any system at any price, you simply must audition the HCA-2.—Kal Rubinson

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