Research for subwoofer

What kind of budget range are you looking at?

+1 REL but, specifically, REL T9/x given the size of your room.  Compared to its peers, REL sub has lower group delay and integrates better with the main.  I have tried SVS too.

Thanks for all the input Sounds like you have narrowed the field for me and given me great things to try.  I look forward to the experiments that are about to happen.

Budget I was looking at depended on what folks said.  From what I see I can do many of the suggestions for under 1400 and that would work well for me If I hear a real improvement.

No better value than prices on the last gen REL Carbon Special. 

For your room size I would suggest the REL S Series if you go with REL.  They are expensive though as in >$3k.  You’d likely be better off with some Rhythmik subs.  Easier on the pocket and excellent performance.  I have a couple of RELs (T5/x) for my small space and they are outstanding but would get swallowed by your room.  The T9/x would might be sufficient with two or more but they only go down to 27Hz.  Something like the S550 goes down to 19Hz.  The Rhythmiks play low like the S550 but at a fraction of the cost.