I have recently replaced my concert head unit in my 2006 A3 with an aftermarket kenwood unit. The problem i am having is the rear speakers seem a little quiet, and the radio reception is rubbish! Every thread on here points towards an aerial booster adaper which i already have installed, so I am looking for a little extra help. I have currently installed: Harness PC9-401 (I believe my system is half amped, although this harness leaves the rear speakers very quiet and a little crackly.) and Aerial adapter PC5-137 (This uses the Fakra connection but leaves me unsure what to do with the ISO aerial connection, if anything?) I have managed to overcome the volume difference in the front and rear speakers using the channel balancing feature, reducing the volume in the fronts, and using a slightly rear biased fader setting, but doesnt eliminate the slight crackle. The aerial adapter I have tried connecting the blue remote wire to the amp remote, and a 12v feed, which both give poor results. Have I missed anything? or is there anything i can try/check? I don't normally listen to the radio other than for the odd traffic report, but having thought i wouldn't miss it if it wasn't there, It's getting kind of annoying! Thanks!