pioneer hd unit no sound out of speakers

I recently purchased a car with a pioneer head unit in it. The sound was working fine until today the head unit is on and the sound just cut out but the headunit is still on and says it is playing. No radio or CD plays audio. I reset the car and it comes on for a few min. then all of a sudden no sound... I checked the wiring and everything looks fine nothing shorting out. messed around with the head unit and no luck only when I turn the car off then back on sometimes does the sound work briefly. Any suggestions? Head unit amplifier going bad?

Did you recently install any speakers in the car?  

yes 2 rear speakers but they were working fine...

Inspect the wiring on those speakers.  Make sure that you do not have a grounded speaker wire.

either that or one of your other speakers is blown or grounding out.

yeah i had that happen with my car, i didnt have the rear speakers mounted and when the bass would hit, the vibration would cause the speaker terminal to touch the exposed metal of my cars frame which would in turn ground the channels out. the subs did still work even when the highs/mids would cut out so if you have subs in the vehicle and you are experiencing the same thing that i described you may wanna look closely for speakers grounding out.Boosh