Mac 402 or 501 for B&W 802D?

I went to a dealer who had 802d so I could hear the Mc sound. Not sure whether it was 270W or the 402 but it did not have near the control that my Krell has. Bass was muddy and the mids undefined. That said, I would still like to hear the 501's to see what they sound like.

Why so much power? How large is the listening room? I have the same speakers and find they are satisfactorily driven by my Cary 7B cinema amp with 100w, although most of the time I use my Krell 400xi with 200. My room is 14 X26 sitting at 9' I wonder if I am missing something or the whole power thing is a little out of control.