As soix said, you need to be looking at 2 subs without question. I would drill down on both REL and Rythmik's websites. Solid choices from top to bottom. I have a pair of Rythmik G22's and absolutely love em. They're a dual-opposed 12" model. They also make a dual 15" (G25). They're known for being smooth and easy to listen to, and I can back that up. The balls-to-the-wall home theater junkies think they don't have enough tactile response, and maybe they don't for that application, but that's exactly what drew me to them. The last thing I wanted was subs that draw attention to themselves. The goal is for it to sound like your speakers are producing all that bass.
