Audio Systems: Audi audio replacement, audi radios, auxiliary input adapters

Question
My son wants to upgrade his symphony audio system in his 03 Audi A4. The installers at Car toys said that the symphony amp would not work with a aftermarket stereo. If they bypassed it, they would have to rewire all the speakers and the rear sub wouldn't work. Does this make sense? My son wanted a stereo with ipod connections plus Hd radio and bluetooth. The car toys guys said they couldn't help me. Any suggestions? The system has a 6 disc cd player included in the dash. Thanks!

Answer
This is a sticky problem.  The CarToys people are probably right.  See this page as it may give you some further enlightenment:

http://www.ibiblio.org/tkan/audi/radios/

And, see here:

http://www.oemautosound.com/c-143-audi-products.aspx

for auxiliary input adapters if all he wants to do is ad an iPod connection.  Also, the experts at Crutchfield.com are theee verrry best at knowing all about the connections and interface of various stuff to stuff.  

But, in the long run, he may need a complete system overall.  Most European cars are a mystery to work with - even for the experts in Germany! They are as bad as Bose here in the USA who uses all non-standard specifications!

Best wishes.  Hope this helps.