I think there's lots of good advice here. If you don't have room correction in your system, focus on that first. It's included in the Velo DD series, but -as dbphd noted - also available separately in the Velodyne SMS-1. You can also get similar bass region DRC in the SVS/Audyssey box. The latter costs a bit more and requires a crossover unit ahead of it, while the SMS-1 has a built in high cut(that is pretty primitive and not worth putting in the min signal path IMHO).
Main point - if you don't have DRC, get it! Either included in the DD series or separately to use with the sub(s) of your choice.
Marty
PS I use an NHT x-2 x-over with the SMS-1 and 2 Rythmik subs. Works spectacularly well, but does require 3 components to acheive x-over and DRC (Pre-amp+nht+SMS) for bass region only DRC . An Audyssey equipped Pre-Pro would provide full range DRC in a single box and full flexibility in your choice of subs.
Main point - if you don't have DRC, get it! Either included in the DD series or separately to use with the sub(s) of your choice.
Marty
PS I use an NHT x-2 x-over with the SMS-1 and 2 Rythmik subs. Works spectacularly well, but does require 3 components to acheive x-over and DRC (Pre-amp+nht+SMS) for bass region only DRC . An Audyssey equipped Pre-Pro would provide full range DRC in a single box and full flexibility in your choice of subs.