One last comment on this to back up my homie edogg.
NB67 (chayne) and I both agree that the quad LMS Ultra's do sound different then our systems in that there is more detail to the bass. I win the war on SPL and shake factor which is greatly helped by having the system on the second floor. It is probably a tie with Chayne though now that he has added a pair of dual opposed 18" daytons to his Submersive pair but he is on a slab. I think Chaynes new house will have the media room on the second floor so I have to step my game up
I had a pair of sealed LMS Ultra's before and sold them because I wanted more SPL and was a little bummed these expensive drivers didn't give me what I wanted. When edogg added another pair to his set-up to make it quads that's when I had a DOH moment, I wish I would have kept my pair and added another pair. It was a big difference in edogg's system when adding the second pair of LMS, a lot more than I was expecting.