Fred, I think he is building a Rythmik. That receiver should work fine, but I would wait until you get a few other opinions from current owners. Historically, Onkyo has not had a great track record with the m80 4ohm design and gets mixed reviews. Later models seem to do better. On paper it looks good, but in the real world some have had issues.

My room is 1,000 cu ft bigger than yours, and I've used both m60's and m80's, in either case they will both do a great job.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85