I have a dsx-s100 in my car, it was properly fitted by professional, after about 2 weeks I noticed a sound coming from the stereo, but it sounds like itsa spark-like sound coming from behind, where it is all connected, had a halfords fitter look at it and he said its fitted properly and no problems but it worries me when it gets quite loud, I turn my music up 2 try to drain the sound out, bad I know, I dont know what to do about it, please help, Amy