Hi lleeds,
Remember that the M80s are 4 ohms, so lots of Class A/B power amplifiers will deliver almost twice as much power into 4 ohms. But it's really a matter of room size and your personal taste in loud, clean playback levels. In a really big room, 6,000 cu ft. or larger, it's easy to run out of power even with big amplifiers.
At an Axiom party the other night, one of the revelers cranked up the M80s (plus two EP600s, two VP150s and four QS8s), running in 7.2 (it was already very loud, but clean) and managed to shut down two of the five Denon monoblocs, each delivering 350 watts into 4 ohms. (As that happened, I was shouting "it's too LOUD!") And it was too loud, but two of the amplifiers were clipping and I heard it.
Of course, in a smaller room, an AV receiver with 120 watts per channel will deliver ample clean power and the M80s will respond with sound levels that will satisfy lots of listeners--but not everyone. Until the reveler increased the volume, seven of us were enjoying very loud clean music playback. It was a DVD of Eric Clapton, Billy Preston, Steve ? on drums, doing lots of Robert Johnson blues in a studio session.
Besides Parasound, look at Anthem.
