Jeffc,
If you are looking for a sub that has tight but not boomy bass, I agree with sdcampbell, on the Vandersteen 2Wq. It blends seamlessly and adds a bottom end that you didn't know your were missing. Vandersteen also make a HT version of the 2Wq called the V2W. It adds a 12" passive radiator for additional punch in movies. As for me, I have both mated to my Magnepan/JM Lab HT/Stereo.
If you are looking for a sub that has tight but not boomy bass, I agree with sdcampbell, on the Vandersteen 2Wq. It blends seamlessly and adds a bottom end that you didn't know your were missing. Vandersteen also make a HT version of the 2Wq called the V2W. It adds a 12" passive radiator for additional punch in movies. As for me, I have both mated to my Magnepan/JM Lab HT/Stereo.