Anonymous posted an answer for this Kenwood DNX8120 DVD Navigation Receiver Car Video Player:
"if you go to audio...you'll find "zone" press it and it will give you zone 1 and zone 2...."
Anonymous posted an answer for this Panasonic CQ-DVR909U Car DVD Player:
"look at the install diagram(wiring codes) that came with the unit. if it has a wire that's..."