By the way, I recently ready this (written by the guy who designed the J L Audio CR-1, among other things, as I understand it) about the correct way to actually implement subwoofers, and found it totally fascinating and useful, just thought others might be interested - All About Subs Whitepaper. Particularly found the part about phase, and needing more than just a simple +/- switch to do the job properly very useful, as is the part about ported mains/subs...