I am in the process of replacing the dying Symphony head unit in my A6 and have a couple of questions. First of all, there is a great write-up from Nevalite in another post that gives specific wiring instructions / wire coding for a 2001 A4 (same setup) at:

https://www.audiforums.com/forum/b5-...arness-147780/

I followed his wiring diagram (after buying a kit off Ebay) and it worked brilliantly, though a couple of points were omitted. Concerning the amplified antenna, I know the correct adapter is needed, the Scosche VWA2B should be the correct unit, which I have on order. There are 2 connections that need to be made from the adapter - the actual antenna connection is straightforward, and if I'm not mistaken the other wire should go to a switched 12V power source. There is also a wire that was hooked into the back of the radio that was wrapped in with the factory antenna lead that has me stumped (and is probably not needed), but it looked like a mini-antenna connection that has a metal square head on the connector - any ideas what this is? Also, there was a brown ground wire connected to a spade connection on the back of the factory radio, does this need to be reconnected to a ground? I was wondering if it was part of the amplified antenna assembly.

Also, when replacing the front speakers (also dying), the wiring color codes on my car were green/black positive, black negative. I bought JBL GTO628 6.5" speakers, they are a perfect fit with the supplied adapters and sound great. These were one of very few speakers I could find with the correct adapters. I left the factory tweeters in place, they work fine in tandem with the JBLs.

So far I have had no issues - the JBLs, factory rear speakers and sub work great with the JVC KD-X50BT head unit I chose - I just need to get this antenna thing settled.