I know the subject of radio reception on retrofitted RNS-E has been covered a hundred times but I've followed all of the advice I can find and I'm still having problems so please bare with me!
Bought my car (2008 58 plate facelift S3 sportback) about 2 years ago with the standard Concert Stereo. I immediately upgraded to an RNS-E and added Bluetooth. The radio was then virtually useless (could just about manage Radio 1 and local BBC Berkshire but not a lot else) - I couldn't bring myself to shell out the best part of 200 quid for the aerial amplifiers so I just put up with it and mostly listened to MP3's.
A couple of months ago I finally decided to sort out the radio - I bought all the bits (new, from Audi) and followed the guide here:
Converting symphony II antenna system use with RNSe
Radio performance is a lot better than it was but it still seems to be struggling and it's nowhere near as good as I would expect. I now get a long list of stations but they are constantly coming and going and are often greyed out. I spend a lot of my time in the Reading / Slough / M4 area and in other cars I can receive most of the London stations (Absolute, Capital, XFM, Heart, etc.) everywhere I go but in the Audi these stations are either greyed out or have a lot of static (I've never even seen XFM in the station list). Is the reception with the RNS-E and the diversity antenna normally poor or do others get better results?
Another strange observation which may well be relevant is that if I plug my phone into the 12v socket in the centre console to charge the radio reception gets noticeably worse. My only idea on this was that it could be related to the Aux In socket which is very close to the 12v socket. I remember reading that the Aux In wiring needs to be modified to work with the RNS-E - I have never modified it since I don't use the socket, could this be causing Radio problems?
TBH I was expecting a lot better performance after coughing up the money for the new diversity amplifiers - I've had better results in the past with ten quid aerials from Halfords!