Charles, sorry your not as pleased with the 80's at this point in time. I'm pretty sure the issue is your Sony. Most people will use Denon, HK, or other methods that have been proven to have no problems with the 80 4ohm load. Not sure if you asked those questions when looking at speakers, but I'm sure we all would have said the Sony would have problems.
Yes, you could by some monoblocks for the 80's and drive the rest of your system with the Sony, but I think long term you may find you'll want a different AVR and/or seperates.
I'm sure others will chime in here, but most Denon's, HK's, NAD will have no problems driving the m80's. If you have the money and want to go the seperates route, go for it. At this point my Denon 2805 has no problems driving my 7 Axiom speakers. Some day I'll most likely get some 80's to replace my 60's, however, right now my 60's have no problems in my 900 sq ft room.
