I love my QSD but despite the owner's manual can;t get the mp3 jack to play through.../

Help? The manual is a bit light on detail. I feel like a moron but after an hour toying with it - i need some insight.

Use a stereo mini-jack 1/8" male to male cable (stereo will have 2 black rings on it, mono has only 1 black ring). Make sure it has 2 black rings. On channel 4, move your input switch to the left most position (aux 4). At this point you should be able to play through channel 4 from your MP3 player.