Hello together, even if there was a similar topic here, my case is a little different and I would like to know if there are some clear clues about the cause: For a few weeks (I have the impression, since a service on the roof) the rear speakers of my premium sound system only sound like telephone speakers. Very “potty” and quite quiet. At the front I have fas when moving the fader (yes, surround and EQ and subwoofer is all out for testing) t the double volume on the speakers like back. Supposedly, after my complaint, a software update was made, but the change was in my opinion only minimal. I think rather that there is somewhere a cable on the amplifier not correctly connected or something like that in the direction. Or an amplifier defect… Where exactly and how could I quickly narrow down what it actually is? Is there anything I – without completely disassembly the car – myself check I know it’s probably whining at a high level, but I’m sure the system had more “pressure” before. Everything seems to be OK at the front, actually only with the rear speakers as described. And I would have liked to fix that before VolvoPro expires in September and I have to pay for every screw to tighten… Thank you for every tip!