[greenkit]

Ok Sean,
That's most helpful, many thanks for doing this test. I'll go back and make a few more measurements later this week. I was aware that the driver's ground path was a bit convoluted: will check this and the other plugs/sockets involved in the audio path for good continuity. At least I now know that I'm looking for a result that's achievable. I'll report back in due course.

Noel