There is no substitute for displacement. The REL may be the right choice because it integrates so well and is musical, but you will not be happy with HT unless you have 2 in your room... or you listen at low levels (U571 was not meant to be listened to at low levels ...) . I am a BIG advocate of stereo subs. Much improved imaging. Further, with 2 subs, MUCH easier to integrate into the room and get it right. I have a dedicated 30x16 room with 15' cathedral ceilings. One sub does not really cut it in term of impact at references levels for HT. Get the REL, get two of them.
