If anyone is still following this thread I bought this adapter:
https://www.connects2.co.uk/Product/...Item/CT51-AU01
It's made specirfically for Audi with BOSE systems and has a built in delay for the bose amplifier to prevent all the pops. It will work with most aftermarket head units.
Once it arrives I will install it and report. If it works I will do a demo video for all the users on the forum.