How low can a 5.5" midbass with 4 mm x-max be used on an OB? My room is small, and SPL for music is usually limited to 90 dB. I want to use it as a mid in a 3-way crossed at about 400 hz. I also have some 8" drivers that I could use. I would like to cross to a dome tweeter at 2k. This will be a passive speaker used with a sub.