I have a Kenwood KDC-X996 in my 2004 f150. i am using all the pre amp outputs with my 4channel and mono channel amps. the head unit will work fine, but at random times I will start the car and no sound. the head unit will turn on and all the functions work , just no sound. the amps are turning on to. The only way for me to get sound again is to pull the fuse on the contestant 12v and reset the head unit memory. Does anyone know what causes this or is it a faulty head unit ?