I have the same problem. I've been thinking about taking it appart and either putting some dynamat in it or some kind of fire proof foam that would absorb shock...
I have the factory compass auto -tint and it vibrates /rattles under normal driving.My wife wants to know if I can swap it out from my 06 to her saab 92x.
All you need is to trade it out for the standard mirrior on the base model that is what we did I just traded with another wrx in the area now there is no rattle and thats with two 12s.
I looked since I wanted to swap with wife regular mirror. How does it come off???...Was worried about creasing/warping headliner trying to see connector.