Help with Sereo in 2004 Monterey
 

I recently purchased a 2004 Monterey. We like it very much. The only thing we can't seem to figure out is the stereo. This vehicle has the built in DVD system in the roof. We can't figure out how to watch a DVD and not have to hear it through the stereo speakers. We have wireless headphones which are useless if we have to listen to the movie through the stereo. Any help is appreciated. Thanks.