New head unit and res help

[jhurd]

My factory disc changer went out and wanting to replace with new dvd unit. I have the factory rear entertainment system (res). I have been told that i would lose the option of listening to the res when i replace the factory unit because it plays thru the factory unit and not after market units.

Any help? I dont want to replace the res just wanting to upgrade head unit to a touch screen dvd/double bin radio head unit/