I bought one of the early HCA-2 amps and am basically very happy with it. I'm still breaking-in other parts of the system, so I'm not 100% certain I've achieved best sound yet. But in that regard, buried in a thread on the PS Audio website is an offer to upgrade any of the early HCA-2 amps with either the letter C or D in the serial number. The mod is free and provides a little more air and space between the instruments. Minor, but noticeable, so why not get the upgrade, especially since PS Audio throws in a free Powerport for you trouble. The mod was apparently something that they discovered in response to the comments about the long break-in required by this amp to sound it's best. I found it improved continuously through at least 100 hours of use, and maybe more.
I also found it's extremely sensitive to the quality of the power cord. I replaced the stock cord with a Mini Lab Cable with good result, but when I heard my amp hooked-up to my friend's well broken in Lab Cable, I had to buy one. There is a noticeable improvement in the decay of notes and a richer, fuller sound, especially on piano. This from an amp that runs cool to the touch, go figure. The amp is priced so right, I'd advise anybody thinking of buying an HCA-2 to include a Lab Cable, or some other comparable killer power cord in the purchase price to enjoy the full capability of this amp. You're still out the door for about $2000 and laughing all the way home.
I also found it's extremely sensitive to the quality of the power cord. I replaced the stock cord with a Mini Lab Cable with good result, but when I heard my amp hooked-up to my friend's well broken in Lab Cable, I had to buy one. There is a noticeable improvement in the decay of notes and a richer, fuller sound, especially on piano. This from an amp that runs cool to the touch, go figure. The amp is priced so right, I'd advise anybody thinking of buying an HCA-2 to include a Lab Cable, or some other comparable killer power cord in the purchase price to enjoy the full capability of this amp. You're still out the door for about $2000 and laughing all the way home.