I have not experienced that problem in the sub. Somewhere in the affordable sub threads it was mentioned that the cover pegs/ holes will sometimes rattle a bit, also check your sub's feet for tightness. I have been using the Disney Wow disc for calibration and it has test tones to help find vibrations in your room and equipment maybe something like that would help isolate where the problem is? I had rattles from a cabinet door and pretty bad in the interior grade door to the store room. Kind of like tracking down which smoke detector is beeping it is a bit of a hunt. Still convinced this is the best sub for under $600 and fairly mid level for $700 most of us (including me) bought it for 300. I am super happy with mine. If we were going to spend $900 on a sub-woofer then we wouldn't be in this thread.
I'm positive if you upped your budget to 500 dollars you'd find a sub much better than this. Saying this 300 dollar sub beats subs for 600 is a stretch lol. I do have a LOT of things vibrating in my room. My door goes INSANE when I play music. I was just only using my towers (Haven't received the RCA cables to hook my amp up to my receiver so running just off my amplifier), and the door wouldn't stop going crazy. That's just one of the few things that rattles. But I can tell the difference between sub problem and rattling in my room and something is off.