Marc,
Hello & welcome. I am driving the M80's with a Yamaha 5660 with no issues. I can turn it up to -15 and it is very loud. (Sorry no dB meter) I only listen at that level by myself, as it is too loud for the rest of the family. I have tried going higher but it starts to distort, and all the joy I was feeling - leaves. It runs fairly warm, but I have yet to have it shut down. The key is that I am in a room that is only 16 x 18 x 8.
Randy hit it on the head - If you are going to have the system in a fairly large room, (and you like it really loud), the Yammy & the 80's are not a wise choice. Either buy the 60's or get a new receiver.
As a side note, I am having a new house built. The system will be in about twice the size of room, AND half of it has 16ft ceilings. We'll see how the Yamaha holds up. I see a separate power amp in my future.
Shawn
