Hi there,
I started with 2 with the thinking that the room isn't sealed (a kitchenette off the back and an open hallway to the side), and that 2 subs would yield a more uniform bass response throughout the room. Once I got the 500s and heard what they could do, I'm not sure I needed 2, but it's one of those things you'd never give up once there. I started them out with one up front and one in the back of the theater. I ran them this way for over a year. I later got the SMS-1 and looked at placement again. I did lots of tests and found that they seemed to do just as well up front. Overall I liked the setup better this way.
Now on the subject of one vs. two- I did my best to A/B compare and found if they are calibrated right I don't notice the difference at all from my main seat. The main benefit is some extra SPL when the EP500 is driven to it's max. I'm getting about a 5 dB boost with the 2nd sub. I think for a large space or a room that isn't sealed off from the rest of the house/basement, it's worth it. Otherwise, one good sub, placed and calibrated optimaly, would do the job. Really a tough question as there are so many factors.
I'm in South Jordan, not too far from 90th So. and Bangerter. Let me know if you want to come by and listen to the EP500.
