Both Denon and Onkyo are rolling out their new models so now is actually a good time to get one of this years. The Denon 3807 is solid as is the Onkyo 3007 (which I presently use with my 3 M80s and either 6 QS8s or 4 QS7s and 2 M2s depending on if I’m using the height or wide option).
Like Alan said to get the most out of the M80s in a large room a separate Amp doesn’t hurt but your going to want a good modern receiver anyway so I would get one of those now and if you find you want things louder and still sounding clean you can always add an amp/amps later. A couple forum member are using the Emotiva XPA-3 to run their 3 front speaker while using the receiver to run the surrounds and rears. However, IMO anything in the Denon 3808 or Onkyo 3007 range or higher should be fine driving 2 M80s a VP180 and surrounds/rears in your room at 85-90dB average which over time will cause hearing loss because of how loud it is.
As for which is better Denon or Onkyo I thinks it’s a matter of what you want. As I posted previously my experience is that Denons will not shut down before are damaging your speakers where as Onkyos will. Another poster at AVS damaged his M60s using a Denon 2807 for this very reason. More generally I feel that Denon’s features lean more toward the power user or tweaker as the controls are more easily customized. OTOH Onkyo is more geared toward the casual user. They do the same things as the Denons just not always as easy to customize since the Onkyo takes care of more things for you so it’s not always as easy to tweak but easier to run out of the box.
Cheers,
Dean
