Hi, All. I finally resolved all issues with fitting an aftermarket radio to my SAAB 9-3 Aero. Previous unwanted hums and background noises have been eliminated. Kit used is as follows:
Autoleads FB-32-03 Facia adaptor single din
Autoleads PC9-415 Harness adaptor for use with amplified system
Autoleads DAB-AA1 Windscreen aerial fitted to the A pillar and positioned vertically.
Radio World Ground loop isolators (2 needed)
Sony MEX N 6002 BD Head Unit
The plug in GR Isolators fit between the head unit RCA outs and the harness adaptors and eliminated all noises from the signal - excellent result.
This install has been difficult but simple when you obtain the correct items. The Sony worked much better than a Pioneer unit on trial.
Hope this helps someone in a similar situation as the reward is a superb DAB/FM/Bluetooth/ USB/CD player installation with 220 watts output.