My stereo makes high pitch noises??? I have a sony stereo, 4 channel rockford amp going directly to all 4 of my speakers. It only makes the high pitch noise when i drive. As the rpm goes up, the louder and higher the pitch is. Does anyone know what it could be, heard it was grounding, but kinda of wierd it only happens when i drive. I've checked the following grounds, Amp, Stereo Grounds.