i tried a rel stratus in a big room - one-note-thump. my brother-in-law tried it in a small room (he'd actually purchased it) w/a pair of proac response 1.5's. the soundstage collapsed, & the details were hidden. he sold it after a week after purchase...
for *real* bass that won't break the bank, get a vmps sub, w/outboard electronics - far better quality electronics for the money, than what's included in powered products. i like my marchand xm-9 x-over w/upgraded op amps, & my pair of vmps larger subs w/options. i have been able to successfully audition many different speakers in my rig w/the amazingly flexible, transparent marchand unit. amps? choose any decent used s/s amp. *real* bass, clean, undistorted, high spl's. check out vmps' & marchand's www's. oh yeah, if you only want *one* sub, the original & larger vmps models allow for use of a stereo amp, w/one channel driving each separate driver...
doug s., yust a satisfied customer...
ps - i don't *own* a ht set-up, btw - my system is audio-only...