I just moved and have set-up my HT in an open floorplan living room (= large space). Everyone says that I will need two subs to fill the space. When I ran Pioneer's auto calibration, it kept telling me to turn my current sub's (Cerwin Vega LW-12) output down. I ended up with the volume of the sub set to about 25%. I guess that I am confused as to why I should be using two subs when I'm currently only using 25% of my current sub's output.
BTW- I plan to purchase an RW-12 from Newegg while it is on sale again. If I can get the two to play nice, I'll use both; if not, I'll use the CV elsewhere.