30X40X12 is a very large room - 14,400 ft3, Two big subwoofers are a necessity to fill a space like that. My only complaints with REL are lack of continuous phase adjustment and their ignoring basic best practices for biamping. To be done properly, there needs to be a line-level crossover that rolls the mains off and rolls the subwoofer in, No speaker-level driven subwoofer can do this. Most HT Amps and preamps accomplish this via a Low Frequency Effects (LFE) output and Bass management - adjustable crossover frequency, level, and phase, often combined with Audyssey or Dirac equalization.. Some sub manufacturers put these electronics in the sub, but this requires 2 sets of interconnects - to the subs and then back to the main power amps. Certainly less than ideal, given that the subs may have to be located some distance from the preamps and power amps. This is problematic electronically, and the interconnect costs may be very significant.
As for me, I am awaiting for a high-end preamp with proper LFE and *shocking* a variable loudness control. Yamaha has demonstrated the utility of that for decades. To their credit, Parasound comes about as close as I have been able to find.