The reason people find the MC-352 to sound better than the MC-500 is the design and configuration of the 352 is better than that of the older 500. The 352 truly sounds better than the 500, but the 602 blows the 352 out of the water.
I better, it is substantially more money. I have owned the MC-500 and went to the 352 and for some time used them to push a pair of Vertias 2.8's, B&W 801II, and recently the 802N's. The 352 is a fabulous amp, AS LONG AS YOU DO NOT have 85-86db speakers. At loud levels (for which I prefer)
it doesn't have the capabilities to push them. There is a set of monoblocks that will sound MUCH better than the 352 for about 1/2 the price of the 352, in used $'s. The older (and very ugly, might I add) Carver Silver 7t's. Ugly, but LOADS of power, headroom, bottom and top end! Very detailed, and if not open the to the nakes eyes, one of the BEST valued amps available at ANY level! For what it is worth, I have to say, I also bought a Citation 7.1 and BIAMPED the 802N's, and THAT sounded better then the 352!
IMHO
Dan