I have noticed from day one an annoying intermittent hiss from the speaker of my 07 QP. It is most obvious from the driver's side front speaker (maybe just because it is closest to me) It occurs whether the mute button is on or not, i.e. it can be heard over the top of music (CD or Radio) and also when the mute button is pressed. It lasts about 5 seconds in length, every couple of minutes. I wonder if it might be some kind of feedback from the electronics in the car. I have tried switching off my cell phone thinking it might be causing some interference as well, but still the hiss is there. The dealer says other QPs do it and there isn't anything to be done. Any thoughts?