I agree with those who say you need to try it for yourself.
I've listened to a lot of Class D amplifiers, and so far, none has ever come close to having me consider a move out of a tube amplifier. To this point, the only two that I have appreciated are the Spectron and Veloce. I've not heard the H20, but would like to. Certainly, if I picked up a pair of Apogee loudspeakers, I'd seriously investigate the H20.
My biggest problems with the lion's share of Class D amplifiers are analogous to the two problems I have with CD. First, while there may be the initial impact of the note in the low frequency, there is simply nothing (or, almost nothing) behind it, leaving the foundation of the music lacking the proper fullness, warmth, and weight. Second, there is something I perceive through the rest of the musical spectrum that for whatever reason, does not allow me to fully relax and immerse myself into the experience. With CD, I've narrowed it down to the music being "chopped up" into not a fine enough material so that the comparison with the way analog flows like water is stark. I have not spent enough time with digital amplifiers yet (the longest I lived with one was 3 weeks) to fully put my finger on it, but there is an inherent lack of emotion in the sound. I don't want to call it coldness per se, as it's not completely that, but producing the flesh and blood of music, is something they so far, miss.
DISCLAIMER: The manufacturers of Veloces are very close friends of mine, so take my opinion with the appropriate grain of salt.
