80hz is fine for movies, LFE are boom and bang anyway. For music you can't get away with the boom and bang thing. If you can set your processor at one set point for movies and another set point for music then you are all set. For music, find the point where your speakers roll off big time in the bass, set the crossover as close to that point as you can get, buy a cheap spl meter from radio shack at the very least to set up. The idea is to bring the bass in were the other speakers leave off, this point is always near the point of spl. fall off of the main speakers. If you set to high you will have to much bass, if you set to low , you could leave a hole with no sound in that range until the sub kicks in. You must work very hard at it to be happy, I have a hate/love thing with subs.