Hi Marc
This is my first posted reply - just joined the Axiom club yesterday.
I have M60ti's (8-Ohms) and they will play as loud and faithfully as you will ever need in all but the largest room. However, if you're sold on the M80s, your Yamaha receiver has an 8-Ohm/4-Ohm switch on the back panel that reduces the overall power output but prevents overload. The M80s are more efficient that the M60s so you should be able to achieve similar SPLs. My sister has a Yamaha 5760 driving her 4-Ohm Paradigms and has no problems.
