I've got to go against the grain here. No amplifier change I've ever experienced comes close to effecting the degree of sonic differences that a change in speakers can make. Obviously, this is not a popular position, but I firmly believe that after the recording and the room, the speakers make the biggest difference. And any change in amplification will produce, at best, a modest difference (unless, of course the amp and speakers are mismatched).
-Bob
-Bob