Ive got the same system as you, except with a yahama 557 and a axiom ep500 for my sub...I would say def look into axiom or SVS for a sub, the ep500 has made my system what I had dreamed it would be, and my room is a bit larger than yours. Only reason I didnt get the plus/2 from svs was because im in college and will be moving alot, so the 140 pounder didnt make sense, but I can't imagine needing more bass than the ep500 allows, i live in apartments/townhouse style homes and my neighbor three houses down said I knocked all the paintings off his wall my first day with the ep500