looking to replace what I now know is the basic chorus with no rear speakers in a 2009 a3 sportback (8P I think). Have just seen a synphony changer from a 2009 a3 quattro. Does any one know if it will just be a straight replacement, or is there more to it. I know I won't get any sound from the rear until I get some speakers fitted, but will it work with just the front ones to keep me going. they are looking for £75 plus postage for it, is that reasonable. Any advice will be greatly appreciated.