And not to sound condescending at all, but make sure it IS the sub! Quite a few times over the last several years, someone has posted that their sub is rattling, but really it was something in the room.

I assume that's NOT the case here since you specifically isolate it to the back panel, but I thought I'd mention it just in case! smile

::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::