some speakers need better amps than others...with my old klipsch speakers the more amp power I gave them the worse they sounded. my focals like something better than avr power, but cant take uber amps...maybe 300 watts. Im perfectly happy with my nad amps, but by no means are they the best or worst. only amps I can say I can hear everytime is simaudio but they pricey....if you get a 400 crown amp that works for ya, congrats. one problem solved.
Power: Marantz sr7008, NAD C 275Bee x 2, Video: Oppo 103, Samsung 75un6300
Speakers: Focal aria 948, Focal cc900, Klipsch synergy KSF 10.5, Magnepan LRS
Subs: Rythmik FV25HP, Rythmik FV15HP