I currently have a JBL PSW1000, and it's just not cutting it. I typically like the tight sound of sealed subs better then the sloppy sound of ported subs. However, I have not heard a properly built ported enclosure. I've only heard retail boxes which are usually small and ported around 35 or 40Hz. I am contemplating building a 15" sealed Quatro in a ~3 cu ft box or a 12" Quatro in a ~3 cu ft box ported at 20 Hz. I use my system about 85% for HT, and about 15% for music. Whichever I end up building will be powered with a 240W plate amp from PE. What are the drawbacks or advantages for each of these designs? With room gain and a BFD, would I be able to get enough boost in the 20-40Hz range to achieve a relatively flat response from the sealed 15"?