Any A3/A4 head unit has only one audio in (if any), that's the one for the CD changer. Audi did update the software in their 2004 head units to support a SAT receiver but this is still using the CDC audio in. In order to install a CDC, the SAT receiver has an audio in for the CDC. Which results in being able to control 2 audio devices, the first being the SAT receiver (audio in to the head unit and controlled via CAN), the second being the CDC (Audio in to the SAT receiver and controlled via CDC Data/Clock/enable on the head unit).
Any interface/adapter for an iPod is using the CDC audio in. This is easy if you don't have SAT or CDC, simply plug it in to the CDC port on the head unit. But if you have SAT (installed or prewired) then the audio in is already used and you would need to route three wires (audio left/right/ground) from the head unit to the SAT receiver.
This is the reason why they all say it's not compatible with SAT or CDC installed, the first because the audio wires to the back are missing, the latter because the port is already used. And the same is true for Phatbox, Icelink, Blitz, even if you want an external OEM CD changer and already have SAT.
It is still possible in many situations, just not plug and play.
Any interface/adapter for an iPod is using the CDC audio in. This is easy if you don't have SAT or CDC, simply plug it in to the CDC port on the head unit. But if you have SAT (installed or prewired) then the audio in is already used and you would need to route three wires (audio left/right/ground) from the head unit to the SAT receiver.
This is the reason why they all say it's not compatible with SAT or CDC installed, the first because the audio wires to the back are missing, the latter because the port is already used. And the same is true for Phatbox, Icelink, Blitz, even if you want an external OEM CD changer and already have SAT.
It is still possible in many situations, just not plug and play.
