Ask this same question in the Solid State forum at http://audiokarma.org/forums/. Be sure to indicate the 4ohm impedeance of the M80s. The 1280 is surely a beast of a receiver; the unit was second only to the SX-1980 in Pioneer's line at the end of the 70s during the various manufacturer's Great Receiver Wars of the day. These fellas ought to satisfy your inquiry. Best of luck, and cheers.

DS.