Grab a cheap portable CD player, and have the AUX line on the empeg easially accessable. Works onders, until you leave that portable CD player in a hotel in Austin.
Lately if it became absolutly critical for anyone to play a CD, I have my laptop with me most of the time. It doubles as a ripping machine as well
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The best solution though to avoiding friends wanting to use a CD is to get them to buy empegs. That way the only decision that has to be made is who's empeg goes into the dash for the current trip.