I want to send a signal from my guitar processor to my iMac for recording in applications such as Garageband. Using the digital line-out from the processor I tried to connect to iMac using a 3.5mm stereo cable. However, when trying to set up a track in Garageband I could not get an input signal. In the MIDI/Audio app I have set input and output devices to built-in devices, and in sound preferences I have set the track to receive from the line-in jack. I messed around in Garageband with all the input options for the audio track but I still couldn't register a signal, yet my processor LED meter shows it's outputting fine. I really need help here. Do I need a special cable or something? I can't understand why this topic isn't fully addressed in the supporting literature for Garageband or Logic or in the iMac OM. Would appreciate any support I can get.