My current system is all Def Tech.--- BP2004 fronts . CLR2002 center and BP6B rears. Although the fronts have decent bass extension . I would like to supplement it with a "true sub" The system only used for HT . Room is large because its an open concept with family room opening to the large kitchen area. Total area approx 30' X 30' x10 '. The subwoofer can be located behind the system or next to my listing position about 15 ft away. My budget is around $500. Any suggestions? I notice Hsu VTF2/3 , EDesigns A300 , SVS and several others are favorites here. I have to buy without listening as I can find these around my area. Suggestions welcome.