Greg, any amplifier can drive a speaker rated at 4 ohms. The question would be how loud and how long until overheating shut down its protective circuits. For an amplifier to get an "official" rating at 4 ohms under the FTC amplifier regulations it would have to operate into a 4 ohm test load at the full rated power for at least 5 continuous minutes. This is unrealistic in the real world of home listening, of course, and amplifiers not being able to pass such a severe test without shutting down nevertheless have no problem with the M80s and other speakers carrying a 4 ohm rating.
