I was wondering if a two way sub system could give the best of everything below 80Hz. Here is what I mean: let a big sub with a 15 or 18 inch driver handle the stuff from 40 or 50Hz and below and let a small sub with an 8 inch driver handle the stuff from 40 or 50Hz to 80Hz. My reasoning for this is that the larger drivers can dig low down in extension and have a lot of impact, which is a nice feature for movies. But, the subs with larger drivers can sound sloppy and flabby in the 40 to 80 Hz region. But a well designed 8 inch sub can be about as quick and nimble as a sub can get in this 40 to 80Hz region and even lower in extension. The main problem with such a small driver is that it won't have much impact with lower frequency stuff.
A good example of subs that I was thinking of is two Hsu ULS15's and two Axiom ep400's or two Velodyne MiniVee's. Put the Hsu's at the midpoint's of two walls facing each other and the two 8 inch subs at the midpoint of the other two walls facing one another.
With this set up it seems like you would have a flat frequency response, in the bass region, at every seat. The bass would dig down low with a lot of impact, when necessary, and yet be very musical.
What do you guys think? I'm just brainstorming here.