While setting crossovers is good based on the speaker specs as a starting point.....the room itself will dictate which xover is best. My mains play down to 32hz flat....I could use 60hz, 80hz, etc but 100hz was best on overall frequency response of my room. Also my dual 8 inch drivers in my mains can't compete with the sound quality and spl of the subs.
Theater room: Sony 45es | 120" screen | Panasonic BDT500 | Rotel RMB-1077 | Outlaw Audio 976 | Klipsch RP-280F/RP-450C/RP-160M | Funk Audio subs | MiniDSP 2x4HD | Crowson Tech MAs | Surgex XR 315 | GIK room treatment
TV Room: Panny 60 inch | Rotel RMB-1075 | Rotel RSP-1068 | Axiom Audio M60/VP150/QS8 |