Well I took the radio out of my wifes 2004 Audi A4 Cabriolet today and the radio is marked just "Symphony" . I started to install an aftermarket Head unit and ran into a few issues. The first is there appear to be "Two" antenna outputs on the back of the factory Head unit and one is a bigger plug in than the other. That poses a problem because the aftermarket antenna adapter I have plugs into the smaller antenna wire harness from the car, but it has no place to plug in the larger antenna wire. I am assuming there must be two antenna modules but why would each have a different size connection? Any thoughts? I am attaching a picture below to show the two different size wires. The adapter for the 2004 according every picture I have seen is for the smaller wire, then that leaves the larger unhooked. I am too confused about this. Secondly, the wiring harness adapter kit has two different harnesses, neither which will work with the factory plugs. I found another wiring harness kit that looks like it will work, but it is for 96-99 according to the write up but says for symphony radios and the plugs ALL look like they will fit. I don't see bose anywhere on the unit but I do know from the OEM wiring diagram of the system there are rear amplifiers to the speakers. The only speakers powered by the headunit are those on the dash top. Any ideas? Thanks.

 

The picture above shows the two different size wires from the car both for antenna, I think? I know the big one is but the diagram on alldata says intermediate antenna for the littler one. Do I need to buy an antenna adapter that has a power wire to boost the bigger one or just a plain adapter. ALL adapters that say 2004 that I have seen are for the little antenna plug, I cant even find one for the bigger unless I change the year.

 

Turns out the smaller wire is for satellite radio only. The FM antenna is the big plug in the picture and you need a powered adapter to push the module for fm signal. You can get them on ebay or even at best buy for about 10 to 15.00 dollars. Even though the system is not bose, the symphony radio system still has factory amps so the head unit will supply only line out signal with no power, the factory amps will provide that. So installing aftermarket head unit, you can use the Amp control wire to the black 20 pin plug to fire up the factory amps, or if you do not have that wire, you can use your antenna remote wire..either will suffice.