Lee, I would go with the EP500 just for the flat response in a smaller room, it will help keep room effects to a minimum. IF the EP500 is too much money, then by all means get the EP350, it has a farily flat FR as well and is a great performer. I can't remember if this was for a 2 channel system or not? If it is, then I would also suggest the EP400, it is an amazing little sub and adds just the right amount of low end to music, IMO.
The other option would be to look into some other manufacturers subs, like the Paradigm DSP series which are great performers as well, just the finishes may not match unless you get black.
