You can use another audio device, such as a portable digital music player, with your system. This requires using a stereo audio cable with a 3.5 mm (1/8-inch) mini plug (not provided) that is appropriate for the connected audio device that plugs into the AUDIO INPUT connector on the back of the SoundDock® system.
Adding another music source
Insert the audio cable from your audio device into the AUDIO INPUT jack on the back of the SoundDock® system. If your iPod® or iPhone® is not docked, the connected device will play automatically once it sends an audio signal to the SoundDock® system
Set the connected device to full volume, and then use the SoundDock® system volume buttons to adjust the level
on the sounddock® remote, press and hold play/pause for 3 to 5 seconds to enable the connected device to play through the system if your ipod® or iphone® is charging in the dock
The iPod® or iPhone® charges while you are playing audio from the connected device
on the remote, press and release play/pause to switch from the connected device to your docked ipod® or iphone®