I just purchased a 2010 Ford Fusion with the12 speaker Sony radio, and I also noticed a small fluctuation in sound quality while listening to the radio. The sound will go from crisp, clear sound to a more muffled sound, acting as though the stereo signal was being lost or something. The stereo light stays solid, though -- it doesn't flicker or anything. For me, the change is subtle -- I didn't know if I was imagining the problem or not, but my son confirmed that he can hear the change in tone as well. Did the folks that have had this issue have any luck at the dealership?