All,

Just installed a new Pioneer AVIC X920BT head unit in my 2005 SuperCrew pickup. The install went great and all is working as it's supposed to. After our first trip with the kids watching a movie on the rear screen, however, my wife and I decided we need some headphones for the little ones so we don't have to listen to the movie.

Since the AVIC head unit doesn't seem to have a dual-play option for the sound outputs, I'm considering building a bypass system that will pipe audio only to an IR sender for headphones and silence the rest of the truck's speakers and subwoofer.

My first concept is to simply get a bunch of 12V relays from Radio Shack and pipe the speaker signals through them. Energized relays means the audio from the front Left/Right channels goes to the IR transmitter, while the rear Left/Right and Subwoofer remote turn-on signal all go dead. I lose the nav voice prompts, but pushing the de-energize switch on the relays gets it right back when needed.

What am I missing? Is there a better way to switch all the audio channels than using a mechanical relay? Do I need to shunt the rear channels into a resistor rather than a simple open circuit while it's bypassed?

Finally, is there any disadvantage to using the high-power speaker channels coming from the head unit as the input to the IR sender? Should I really be using the pre-amp outputs instead?

Thanks for any advice or lessons learned,

Tom