Sprite, welcome. It's highly likely that the 777 would have more than enough power for the M80s, unless the room was huge and the listening level extremely loud. In fact, it would be advisable not to use the switch in the 4ohm position except in the unlikely circumstance that the receiver would keep shutting down. The 4ohm position reduces the maximum voltage(and therefore the current and power)available and should only be used as a last resort, even with speakers rated at 4 ohms, if the receiver would otherwise start to overheat and shut off.
