Wheeew. Where do I start. I have been slowly upgradeing my existing HT that I put together while I was still in college. I recently ditched my Radio Shack minimus 7s and picked up JBL northridge series speakers (until I can decide on a design for custom built speakers) I have the following: JBL E60- Front L-R JBL EC35- Center JBL E50- Sur L-R, Back L-R I just ordered a Marantz 7.1 Reciever and Marantz DVD player. My goal is to take the fidelity of the entire system up a notch. My current subwoofer is a Kicker Solobaric L7 in a huge ported box tuned low ~25hz and powered by a peavey 8.5c PA amp. Don't get me wrong this sub puts out. It is loud and powerful and very deep. It has lead to things falling off of shelves and breaking in my home. It is however not very musical. I want more fidelity. What I want to do is build a pair of 12" subs that I can put underneath my E60s to elevate them a bit (or not). The subs need to go low, I listen to media with 16hz material (pipe organs) on occasion but I am a fanatic about the lowest octaves. They have to be flat to right around 20Hz. My HT room is about 300 sq ft. I'm not totally locked down to dual 12s although I think I'd like the look. Right now Dayton drivers are on sale so I've been looking at them but none of the product designs have really sparked my attention. I'm wondering if room gain would help me acheive the low notes with a pair of 12s. .. . Any and all input/opinions are welcome. I know I can build a 15" superwoofer, I'd rather not for this project. Thanks.