One of my best friends has a Sonance "The Sub" THX subwoofer. It's listed under "inwall speakers on Sonance's homepage. The problem, besides the fact that it's out of warranty.... When the sub is reproducing sounds (literally any sounds as the crossover only seems to induce MORE crackling the higher it is set), the sub "crackles". I don't know how better to describe this. It sounds like it's cracked or like there is something rattling around in there. We figured it was the speaker, so it was removed, and just to make sure it wasn't the cabinet, it was tried while outside of the cabinet. Still rattles. Got a new 12" sub driver just to check it out (and see what it sounded like), but the rattling (crackling) is still there!! To our minds, that would rule out the speaker being the problem!! Luckily that speaker is returnable. So what else could it be? Electronics in the crossover, the amp?? It's not a dust kind of noise that you sometimes get fiddling with the volume on older equipment, it's just a rattle or a crackle kind of sound. It honestly sounds like a piece of metal rattling or a broken woofer cone or something like that. I don't think that it got any louder with increased volume... To make a long story short....HELP!!! Any ideas for troubleshooting would be greatly appreciated. Thank you all in advance.