The Yamaha can drive the M80's. It's the way that the Yamaha drives the speakers that's in question. As another post in another forum put it, the receiver he was using seemed to blend all the instruments together creating a muddled effect. Using the amp clearly defines and separates the instruments and vocals. In addition when the Yamaha was cranked up the sound becomes increasingly flat and distorts a little bit.
This to me, still sounds like a good reason to not recommend Yamaha for M80's as I do not experience anything like that with either of my Denons.
