I'm very happy with my LS-6's in an 18' x 19' room. I also run dual subs, and am a big fan of multiple subs like you. One can just locate two (or more) subs more optimally in a room than one, and locate better than main speakers (for the low stuff). This will probably be labeled as blasphemy, but I even set my processor crossover at 80 hz. and the LS-6's to small, and so did the auto EQ in my Anthem processor (ARC). I have tried the 6's set as full range, and also tried setting the crossover lower, but keep coming back to small and 80 hz as the best sound for ME. BTW, my room is heavily treated, with 3 large bass traps, a lot of wall panels, and carpet.