PS Audio HCA-2 power amplifier Kal Rubinson Review part 2
Finally, the renovations were complete, the plastic sheets came down, everything was vacuum-cleaned (even the equipment rack), and I settled in to listen to the HCA-2.
The HCA-2 didn't sound any different from what I remembered of the brief initial audition, when it was cold and right out of the box. It did sound strikingly clear, pure, and open. Sure, there was the joy of getting close to my music again after months at more than arm's length—but the HCA-2 was magnetic. It made me want to listen to every recording that I was familiar with, to see if maybe there was something I hadn't heard before.
In many cases, there was. The amount of detail and information conveyed continually amazed me, nor was it due to brightness or highlighting—turning up the levels only made everything bigger and clearer, but not overbearing or glaring. In fact, I always felt compelled to listen at significantly higher levels with the HCA-2 than with my other amps. Had mid- to high-frequency emphasis or peakiness been responsible for the revelation of detail, they would have been obvious and intolerable at those levels.
If cranking it up was the order of the day, did the HCA-2 have the muscle? Yes, indeed. I was influenced by the amp's small size and the more conservative (compared with the manual) power ratings listed on the website, so it took me a while to get the courage to really push it. But when I did, the HCA-2 pumped out power like a nuclear plant. From top to very deep bottom, the PSA was capable of more than my poor little ears could take.
"Mars Extension," from Dean Peer's I think...It's All Good (Turtle 599008), was spacious, with bowling-alley depth, and punctuated with bass that was chest-pounding or earth-moving, as appropriate. Not only was there no evidence of compression even at very high levels, but the HCA-2 seemed to expand the dynamic range compared to other amps. Moreover, no matter how loud or for how long I ran the HCA-2, I never detected anything more than a barely warm draft from the small vent on the left side of the chassis. The power supply of the Nagra PL-L preamp gets a lot hotter than the HCA-2 power amp did at full tilt.
So the HCA-2 was transparent and powerful. Good. But that's not sufficient description for potential purchasers. The important attributes are its renditions of tonality and space, which were distinctive but, perhaps, not incorrect. The HCA-2 did not sound like any of the other amps I had on hand. With the rest of my system components unchanged, the insertion of the HCA-2 greatly expanded the soundstage depth, bringing near voices forward while farther ones remained well back. Scale was maintained, in that the expansion is small for small groups and venues, huge for the opera house. Indeed, if I were mastering a recording, I'd need this sort of resolving power along the longitudinal axis.
The HCA-2 also seemed to minimize room- and placement-dependent irregularities in midbass response. The result was that, with the HCA-2, the Revel Studios sounded more like the B&W Signature 800s did than they do with the other amps. That was a good thing, mostly. It was good, when the rest of the system had the dynamic power to keep up with the amplifier, to re-create musical moments of tremendous weight and power without the midbass blotching of room modes. The juggernaut of an opening scene from Puccini's Turandot, in the spectacular Zubin Mehta recording (Philharmonia of London, Sutherland, Pavarotti, Caballé, Ghiaurov, London/Decca 414 274-2), is enveloping and overwhelming from beginning to end. The HCA-2 created a genuinely theatrical presence at what were, undoubtedly, greater-than-real-life SPLs, but such were the thrills that I couldn't hold back.
It can be a problem, though, if room contributions in the midbass are a needed aid for tonal balance. For example, I tried the HCA-2 in my weekend system, and in that room it was a poor match for the Paradigm Reference Studio/60 loudspeakers. The soundstage, clarity, and power were there in abundance, but the HCA-2 exposed the '60s subtle brightness and the room's thin support in the 100-150Hz range. (Low bass was just fine, though.)
I sampled a dozen or so recordings and got a few kicks (mainly with solo performances), but quickly found the combination of the HCA-2, the Paradigms, and this room fatiguing. Ultimately, it was impossible to determine how much of these mix'n'match results were due to the room itself and how much to the equipment, but it was a relief to return the amplification responsibilities for the '60s to the Bryston 9B-THX.
Things were more than a bit better with the smaller Paradigm Studio/20s. As with many minis, Paradigm has given the '20s a little richness and warmth to balance out the lack of true low bass. Since that's in the very region where the HCA-2 seemed a little reticent, the Studio/20s and the HCA-2 complemented each other. While k.d. lang sounded less than velvety through the Studio/60s on "My Last Cigarette" (from Drag, Warner Bros. 46623-2), she seemed appropriately smoky through the Studio/20s. And with the Paradigm Servo-15 subwoofer below 80Hz, the combo of Studio/20 and HCA-2 was truly superb, with more linear bass from 200Hz down to the depths than I had heard before in this room.
I tossed the HCA-2 back in the car for a return to Manhattan for a face-off with the resident power plants, to play with cables, and to see if another preamp might change my views. I'd been using PS Audio's Lab Cable 2 instead of the standard IEC cord supplied with the HCA-2. Using the regular cord flattened that generous depth of image without affecting the amp's other performance aspects. I also tried a new JPS Aluminata power cord, whose price exceeded that of the amp. With the HCA-2, I could not distinguish the Aluminata from the PS Audio Lab Cable, even though the JPS had been an ear-opener with some other amps, like the Sonic Frontiers, Classé CAM-350, and the eVos.
I'd like to think that the HCA-2's built-in Ultimate Outlet makes power-cord improvements unnecessary beyond a certain level, and that the amp performed optimally with either fancy cable. But I couldn't easily bypass the built-in conditioner, and so could not test this hypothesis. At various times, the balanced interconnects were swapped for others or for Cardas unbalanced, but the personality of the HCA-2 remained as delightful as ever.
When I swapped the Nagra PL-L for the Sonic Frontiers Line-3, it made little difference other than what I've already described in my November 2002 review of the PL-L: The PL-L is just a bit quicker and lighter than the Line-3, and supported and intensified those characteristics in the HCA-2. They may seem an oddly matched couple, but the semiprofessional Nagra and the definitely domestic HCA-2 provided much the same musical balance, one that emphasized transparency without eschewing power. Each, but the HCA-2 more so, was less than emphatic in the midbass and should not be mated with speakers that lack strong midbass output or with rooms with hard acoustics.