I would try the M60s at 60hz and leave the others at 80hz. See how the M60s sound at 60 and if you think it sounded better with them at 80hz then set them back up to 80hz as well. There really is no right or wrong, just take some time, try out different crossovers and see how YOU like the way it sounds, this is all part of the fun of a home theater.


Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70