Hiya, my wife got me a Sony CDX-DAB700U for my birthday a few days ago. I immediately went to ebay for the parts I thought i needed. This is all for a 2003 A4 (B6) replacing a Concert HU, rear-amplified (I think)... I can't see any amp and have a sub along the parcel shelf. I was told a PC9-401 would do the trick - it never. I get a crackling/hissing from the rear drivers side speakers with no volume and the engine off, this is with me joining the AMP REM from the HU into the 401. From what I've been reading a 404 is the one I need? Here is the rear of my new HU... http://i1266.photobucket.com/albums/jj538/redbull1873/IMG_0140.jpg I figured that I would need to join the red and yellow to get it to turn on and off manually, am I correct in saying running a wire from fuse 5 will give me a switched live? Although it's a DAB, I still want to have a good AM/FM just incase, what is the correct ant amp adapter to get? Cheers for any help!