I've just taken delivery of my new head unit and set about installing it today - overall very happy with it: http://www.audi-sport.net/vb/a3-s3-forum-8l-chassis/134427-first-mods-car-stereo.html#post1391738 The only issue I have is that I can't get the rear sub/speakers to work. From what I've managed to read on here I was able to establish I had the non-Bose set up (my stock set up consisted of a Concert I tape heaudnit, CD multi changer in the boot and the non-Bose subwoofer) so I bought the following wiring harnesses: Autoleads PC9-404 (Audi to RCA leads) Autoleads PC5-52 (Aerial adaptor) The following is a picture of the harnesses/connectors in my car: As far as I can tell I've connected them all correctly? - some of the things I noticed were that stock head unit had a small brown spade connector (ground for something?) - which I transferred over onto the chassis of the new head unit. I also have one red connector with one wire left in it which isn't connected to anything?? (is this correct??) I connected the switched/amp signal from the aerial amplifier to the the blue amp signal wire from the pre-out harness and then connected both of these wires to the remote cable from the head unit harness (the below picture was taken pre-connection! LOL!): But when I switch the head unit on - the fronts work but all I can hear from the rear is a static/buzzing noise - when I fade to rear - I hear nothing from the front and just this noise?.. I've disconnected the rears just now - but would like to get to the bottom of this if anyone can help offer any advice??