It looks like you listen at about the same levels that I and probably most people do. We need to know how far back your MLP is located from the M80s. If it is at the rear of your room, it takes a lot of power to attain those levels back there.

I guess that some M80 owners will have to help out here as I don't have those; however, I do know that using a sub or 2 will relieve the towers from the heaviest bass duties & clean up the sound plus will easily give you the level of bass sound that you want. Decent subs dialed in correctly will not sound boomy or flabby.

Of course, that does not tell us why your M80s/system are acting that way unless they are being driven to their limits to produce your desired SPLs at a long distance (if that is the case).

A long shot might be if that particular source material has a bunch of distortion embedded in it that only reveals itself at higher than normal levels.

Interesting condition...

TAM