I've had the M80's for years and have found that between Denon and Harman Kardon, the HK does a slightly better job of driving them.
Be %100 completely sure that whatever you buy can properly power a 4ohm load. The M80's are a very steady 4ohm load, and this will draw more current from an amplifier. Many manufacturers will tell you they can handle a 4ohm load, but in reality, it will limit the amount of current it sends to the speakers in order to handle them properly.
I'm not saying no other receiver can do the job, but just throwing out a word of caution. And, that out of experience, with m80's, I'd pick Harman Kardon, then Denon, then the rest. Don't be fooled by HK's power ratings. A 70wpc from HK is way beyond any other 70 wpc I have ever heard from a receiver in that general price range (I'm excluding amps like Bryston, here).
