if anyone with a vp150 has the fellowship of the ring extended edition bluray, please pop it in and have a listen at around the 2:00 min mark. there is some dialogue ..."and into this ring..." that hits the notes that give off the buzz. play it loud and see if you hear it.
i don't think it's vibrations from the stand as i placed a pillow below the speaker and i still hear the noise (i'll call it a buzz, but i'm not sure that does it justice... but i do think it's some sort of vibration) I also flipped the speaker (which is actually how i had it before) and while there might have been a minimal improvement (probably because it was now pointed slightly up instead of directly at me) the noise was still there.
the more i look into this i think it's a matter of internal resonance in the speaker. could this have developed over time? perhaps the cabinet loosening up? (although the speaker has rarely been moved). perhaps if i removed a driver and stuffed some extra insulation in the interior? would the fact that there is no port on the vp150 lead to some internal resonance?
i'd love to upgrade to a vp160, but that simply won't be happening in the near future
(just upgraded my receiver and have to replace my sub first)