PErsonally id do one big ass loud and clean sub. i had a tc 5200 18 in 3.5cubs @ 34Hz off power from 2kw - 4kw. cleanest/loudest bass ive ever heard. The quality is great, and it's loud as hell. way cleaner soundign than the mt's, btl's, solo x's, and a few other spl woofers ive head. i can only imagine how nice the lms 5400's sound
but thats just me...