I live in a ranch home with 2100 sq ft per level, or 4200 total. My HT/Rec room is about 30 x 31 x 9 with an open hallway into the rest of the basement.
Here is the order of subs I've owned:
350v1 (did well)
then upgraded to an ep500 (night and day difference, awesome performance)
then upgraded to a ep600 out of curiousity (very similar to the 500, just a little more bottom end and more overall presence, keep in mind the enclosure is much larger and takes up more room if you go with the horizontal version)
currently own twin 350v3's in addition to the 600 (this was done to give me a flatter frequency response across all seats and reduce peaks/nulls in the room)
To answer your question, I think you'll be happy with one 500 or 600. Two subs will give you more output and if placed across the room from each other, will help with a flatter response across all seats.
