Hi again Sokratis - nothing I do makes any difference to the bad noise which is on top of my Audya S/PDIF signal.
Please can I just be clear with you about how your's got solved:

1. Did the noise disappear when you changed your Audya soundcard??

2. Did the noise disappear when you changed your PC soundcard??

I've been trying hard for a year now to solve this annoying problem - big thanks for your help!!! Carl