Something's wrong there Murph! I have an Onkyo 797 pushing a pair of M60 type speakers. To say there's no problem is an understatement. The M80s are even more efficient. (Are they 4 ohm speakers? If they are, you have to set your receiver to accommodate them or I think you may burn those channels).

I use an outboard Denon PMA500V 2 channel 85wpc amp for channels 6+7.

Good luck

Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.