Since I've purchased my EP500 I've noticed a highly irritating rattling sound coming from the port during deep bass excursions. When I first purchased it, I wasn't all that bothered, but now that I've finished acoustic treaments in my HT room, everything is great except my EP500. Please note that I am a novice enthusiast in HT. I truly hope my beautiful sub isn't broken.

P.S. The bass volume is scarcely off the dial, and have never raised it to it's max volume.