I was lucky enough to pick this critter up from the FS/FT forum for a good price (thanks!). After spending a little time with it, I have to say I'm pleased. I've tested it with my Beyer DT770pro/80ohm and Senn HD205. Didn't do much for the Senns, but the Beyers seemed to become tighter and more responsive. It did give the highs a bit of a shrill feeling at loud volumes...almost like fingernails on chalkboard kind of feeling....good thing I don't go loud often.
Comparing to the built in sound card on my iMac, drastic improvement on the warmth and tone of the sound coming out. Adding a DAC (Zero DAC) to the picture obviously made a huge improvement too. Right now running with some Svetlana 6C19 tubes and Mullard 8100 in it. Nice, warm sound as you would expect from a tube amp. I did not run the original chinese tubes, nor do I plan to.
It is very sensitive to input power (duh), but it is picking up some weird noise from my battery backup. Its only noticable at low volumes, but still there and quite annoying at times. I suppose I should replace that UPS anyway....
Another great thing about this amp is that there are a ton of threads about this amp, and what tube rolling options there are available. I've greatly enjoyed this amp, and I'm very happy that it was my first tube amp, considering it didnt break my wallet (thanks Head-Fi). I would suggest it to just about anyone considering a low/mid end tube amp.