some folks have said the cable track and the window. I have my cable kinda lifted out of the track for now and still a black tshirt pushing on the window.
I thought a saw a post dedicated just to the rear window rattle. Some folks adding extra felt etc. I just have touched it since the tshirt...
I am very happy with the Unleased system!! came from a 2012 sony, 2015 sony, 2018 B&O and now 21 B&O unleashed. I have always been using a IPod(iphone) with a cable. All sounded really good. I had XM and I will ask if you listem to XM and thne try music with a iphone...always sounded 10x...