Bit odd this. When I connect my iPhone 4S to the aux input on my car stereo I get a very annoying hissing sound coming out of th speakers. It only happens when sound is playing - as soon as sound is terminated the hissing stops. I should add that this only started happening the other day. I got the 4S a couple of weeks ago and it's been absolutely fine up until now. Ive tried my old iPhones (3G and 3GS) and they don't have the problem. It happens with the 4S volume is high or low. Anyone else had this problem? I'm going to try a different 4S tomorrow. Bit weird it only just started happening.