I think in the post on the other forum, myself, Scott (ScottinMA), and John C (Hotsauce) are all referring to the same clicking or rattling noise. Maybe it is more and less aural for some or all owners, but it just makes me think of things rattling... even a little bit... that don't need to.

I have emailed someone from Alpine that has contacted me in the past about this. As soon as I receive a reply I will post any findings here.