I've got a pair of M60's that I use mostly for listening CDs. I listen to all kinds of music in an average room at an undemanding level of volume (one which you could talk over). I am only interested in 2 channels stereo. Budget is around 400$. I have narrowed down choice of integrated amplifiers to NAD 320BEE and Cambridge Audio A500. I would appreciate any feedback/recommendation from current owners.