From the looks of it, you and I have the same lot of speakers and aren't too far off on the crossovers. I set the front two m80s to "full band." I figure short of a room with multiple subs, the m80s put out a good amount of low to help with the load. I've got center on 120Hz, and the surrounds on 80Hz. (also 80Hz on LFE)

I'm watching a film now, but might fiddle around with your settings and see if I notice anything.