problem with ipod audio
 

Has anyone ever experienced a problem when using an ipod connected to a 10 and up base xb headunit. I recently started getting faint pops/cracks in the backgound when playing music fron my ipod using the usb port. Haven't gotten a chance to see if I can recreate the problem using the headphone jack on my itouch and using the aux port. Any suggestions or fixes I should try?