My new ep500 works great.
I was able to run the two together since the old one didn't rattle much unless things got loud....
I tried both subs up front, and one in each corner of the room (front right and rear left)
With both up front their was not a huge change in output. Things did sound smoother and more full from various locations though.
With subs in opposite corners their was a noticeable output boost. However, This location requires the sub to be pretty close to the couch, and it made both couches vibrate pretty good.
In reality, I don't thing the output was that much more than with both subs up front- but the shaking of the couches made it seem a lot louder.
This was neat, but I think that it may get distracting having the sub so close to the couch... particularly for anyone sitting on the loveseat.
I didn't have time to take extensive readings with my spl meter or anything (i took a few) because my girlfriend was trying to do homework.
I will experiment a bit more tonight and then my orginal sub is getting sent back to axiom tomorrow.
based on my quick tests I think that two subs would be nice, although not completely necessary in a room my size.
I like how much my couch was shaking with subs placed in opposite corners, but I think that it would be too much of a distraction after a while. (plus it would be a pain for me to hide the sub cable running all the way to that spot.)
Both subs up front sounded pretty darn good, and it looked the best (according to my girlfriend).
anyway, axioms customer service is top notch. They sent me a brand new ep500 when I told them I Was not even 100% sure I was still having issues.
After doing a quick side by side test last night I think the noise comming from my first 500 was some kind of port noise- but it seemed excessive compared to my replacement sub.