i also have the QSC GX5 and like it a lot; same sound as my Hafler 500, but more powerful and half the weight. there's also the GX3 that's got less power but should be more than sufficient for the M80's.
"An amplifier that adds to or subtracts from the sound quality of the signal it is amplifying is probably defective or badly designed. Or an "audiophile" amp." Bob Lee QSC Audio Products