Avfan, I tried various positions in the beginning from between the TV and my front left speaker, then in the left corner. By the way, my front right side wall has a 4' opening to the foyer.

I decided to follow the advice from Peter T and placed the sub in my sitting position on a piece of plywood, then proceeded to crawl around until I found the best bass. I first used a source with a good recording with a lot of bass drums and guitars and found not much difference along the left side wall from the corner up to my couch. I also used the 990's speaker calibration signal to the sub, set it to 75db and crawled with my Radio Shack meter and actually found my side wall to have the loudest response! I placed a 4" acoustic panel between the wall and the sub to tighten the bass. The sub is not actually mid-wall but actually around 7 feet from the front wall with the room 18' long.

Finally, I mainly use the sub for movies or when playing SACD or D-Audio. Most of the time I listen to music in stereo since my JM Labs have a good bass response and I'm not big on too much bass.

Ron