I'm in the process of building a new theatre room in my home. I plan to use a pair of Cerwin Vega D9's as the mains, which are HUGE with lots of bass. Should I just forgo getting a subwoofer and use the D9's for the bass, or get a sub, in which case the D9's won't be living up to their potential. It's a large room (20x40ft) and I'm sure I'll need a pretty good sized sub if I go that way. Opinions??