I don't run subs because I really don't need them with my Dunlavy SC-V speakers; they're spec'd at -1.5 dB @ 20 Hz. With room gain 16 Hz organ pedal is no problem in my living room. I've thought about buying a pair of good sealed 12" or 15" subs, but really can't justify the expense.
I have a second pair of SC-V in the basement collecting dust and I've thought of robbing the woofers out of them and building a pair of subs. I need to find a way to determine the internal volume of the woofer enclosure(s) that Dunlavy used. I bought a miniDSP a few years ago that I never used, and have a pair of unused Parasound HCA-1200 II amps sitting in the basement that would be great to drive them.