JET777 Welcome.
The first question would be is how large is your room. The Denon will drive the M80's without problem and drive the 60's or 80's to very loud levels. The M80's will go louder than the M60's with or without an amp.
Imo, having owned both the EP350 and the EP500 the EP500 far outclasses the EP350 and is more than worth the price difference.

A computer once beat me at chess, but it was no match for me at kick boxing.