Ok, now for my initial impressions. I have been listening for about only 1 hour so the first thought is that the MC501's sound different then the MC252. The MC252 is a fantastic amp. and different does not mean necessarily better always, but in this case the MC501's sounds better in certain respects and in other respects it may take some getting used to. The reason I have to get used to the MC501's is that they have a very punchy bass, not bloated or flabby but impossible to ignore. I used to have the bass on my C220 turned up to 2 o'clock, now I have the bass either bypassed or even turned down a little bit. Once you accept the powerful bass the next observation is the sound stage . As with the MC252 the stereo imaging is very impressive, however I will go so far as to say my system sounds like I changed more than just the amp. The sound stage is more 3 dimensional. The sound stage with the MC252 was more 2 dimensional ie left/right/top/bottom. When I say 3 dimensional the sound stage extends to left/top,left/bottom,left/side, right/top,right/bottom/right/side and front/back/left/right. As for detail or resolution the MC501's do not disappoint but are still warm sounding and I have to say the MC252 is the same flavor in this department. I am not quite sure I am a fan of the bass at this point as some music is a bit hard to listen to; this may be due to my room. I notice the background is just as quiet as the MC252 was. So do I need to eat crow..... ? I will say that if you asked me a few days ago if I would hear a major difference my answer would be .. NO. Are a pair of the MC501's worth more than double the price of a MC252? To answer this I have to let the amps. break in a little, give me some more time listening. I can say this, if I were able to get my money back on these MC501's and get my MC252 back I would not do it. These MC501's are staying put for longer than the year the MC252 lived with me. Thanks for putting up with my stubborn skeptical posts. Who know's I might even try some cables next.