The M80 is a pretty large speaker, but it's also a 4 ohm load - which means that the 7125 will actually give it 190W, not 125W. I'd be curious to know what people have used to drive M80's over the years. It's very likely that many of them have ended up on receivers whose amps sections are not nearly as capable of dealing with a 4 ohm load and offer far less power than the 7125. That doesn't mean that the 7700 couldn't provide some benefit, but it'd be a useful bit of information (and one that folks around here could probably help with).