I, like so many others visited the JBL tent sale and bought a 4508 enclosure w/2226J's. I am very familar with JBL's reputation, so I bought it primarily because of the "good deal". Now that I have them, I am not sure that they are the "best" drivers for me. I have a 250+ sq. ft. room that I would like to setup for home theater / music. I have 3 Altec Model 14's for mid bass and up and I wanted to use subwoofers in the rear corners. My questions are: would the 7 Pi 15" design work well as a subwoofer only? Can I get lower bass extension by using a larger box? The corner horn configuration seems to extend the bass response. I will Bi-amp with a bridged M2600 Peavey amp (mono low bass), crossover at