Revel 15, or sub 30 or rel stadium III?

Thank you for your response and helping me out. Great place to ask questions and get quick results.

I guess it depends on what you're looking for out of a sub? More for music or movies? Any of the 3 you mentioned will fill a room that size. The Sub 30 will play the loudest and go the deepest. It'll also cost you twice as much as the other 2.

I've directly compared a Stadium III to a B15 and bought the REL. The B15 had more impact and slam. But I preferred the REL's overall extension. Plus it blended perfectly with the speakers (Martin Logans). In fact, I found I didn't like the music nearly as much with the REL turned off, as when it was on. In comparison, the B15 stood out a bit too much.

So if you want a smooth sound for music or movie soundtracks that will also give you plenty of rumble for plane crashes, I'd get the REL. If you want to feel the crashes in your chest and have your walls shake, get the B15.