It may not make that huge of a difference, between 100-300hz, the M80's are below 4ohms.. it will help at the bottom end, where the impedance drops to almost 2 ohms though. lleeds did not say if he has a sub or not.. If he does not have a sub, he may not want to cross over at 80hz.. if the music he is listening to has a substantial amount of material below 50hz, then crossing over at 80hz, will help. However, the 100-300hz range will still stress the amps.
I would be interested in the results of Bluejays recommendation as well.
