I originally went with a Marantz 6002 with my M22s and was not happy with the sound. It was "thin" and underpowered, and this was in a 14x13 foot room. After posting here, Alan (from Axiom, who answered a lot of technical question back then) suggested that the M22 "likes power" and might be better served with a stronger amp. I wound up returning it for a Yamaha 673 and was *much* happier with the sound. I really don't know whether it was the added power or that I just liked the sound of the Yamaha better, but it definitely sounded better.
I'll add that I probably wouldn't have pulled the trigger on the return except that the Marantz was not processing DLNA from my NAS, and that was a deal-breaker as all my music (flacs) was on the NAS. But I'm really glad I did. I know you said you already bought the Marantz, but it might be worth getting something in to compare it with.
