When I bought my M3's this past November, I absolutely loved the them - the detail was incredible when powered by my DENON 2800 receiver. However, when I upgraded the receiver in early December to a H/K 630 - all of a sudden the M3's sounded extremely laid back! I couldn't believe the difference - I always held the opinion that all the banter over "bright" (yamaha), neutral (denon), and warm (h/k) receivers was ridiculous... well not anymore, everyone was right! Oh well, I finally gave in and ordered the "brighter" M22's to better match my H/K - what a great excuse :-)
