I've got my EP175 in a 12.5 x 16 x 9 room, and it's a terrific little sub. For my normal listening levels (rarely over 75db, the occasional 80db), it's more than adequate and never loses its composure. I think the volume on the sub is only dialed up to around 9 o'clock, and that's with the Avia calibration disc. The only negative thing I could say is that in some movies with a lot of low frequency material (particularly a quick bomb blast or something similar), I feel like there's a noticable roll-off. That is, there's no distortion or abruptness in its behavior, but I know for a fact there's additional frequencies the EP175 isn't handling. Of course, my next door neighbor would probably disagree.
If I had it to do over again (and eventually I will), I'd opt for something with more extension. But the EP175 is a very nice, well made little sub and it does very well with music. Heck, it does great with movies too - but there's that 2-3% of the time that I'd wish I'd picked something that could go a little lower.
