Has anyone encountered a buzz coming from the speaker cover/grill on the soundbar? I've read the many posts about the actual soundbar rattling but this isn't that. This is literally the speaker cover. I removed it and drove around and the buzz was gone. By the way, this vibration/buzzing is heard when the radio is completely off.

I tried to put some foam tape between the cover/grill and the speaker itself but that didn't help one bit. I'm not sure now whether it's the plastic cover itself or the screws rattling. All screws are tight and the speaker cover doesn't have any give so not sure what's causing the buzz.

Any suggestions?