I have just got the small PRO 50 and can't decide whether to keep it or not. If I add a second one, will it give me lower frequencies (like the PRO100 is claimed to be). For music it is good and integrates with my mission 734i's well. For movies it definately adds depth, but not at the physical level - ie I can hear but not feel it. For around £600 what is the recommendation; REL or Paradigm Servo 15? (or 2*Pro50) What is the entry point for THX?