I own the NAD M33; I am quite pleased with it. It is well built of quality components, nice feature set, loads of flexibility, and it sounds really good. In terms of sound quality, I prefer my Krell K300i which is a bit more musical, warm, with a remarkable grip/control on the deep bass. But the Krell was 3x the price…
I don’t know how that translates to the M66, but I’d guess it would be similar.