Just acquired a 1998 XK8, love it. Everything works great except the stereo. If volume is turned up it make a buzzing / humming noise,no other sound. If I turn it off and back on again it's ok until I turn it back up again. Would this be the radio or the amp. Also the knob is erratic on the radio when changing settings, fade-balance-volume etc, will go from plus to minus when trying to adjust, . Volume works ok from steering wheel. Help....

 

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