Welcome to the Axiom forum jahusker.

You do have quite a large room. You might want to consider keeping your Onkyo 805 reciever and use it as a pre-processor and look into investing into a 2 channel amplifier for the M80's. The M80's have extremely high power handling capabilities and when feed with enough power will sufficiently fill that room with ease.

Cheers!

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne