Since I didn't really get a definitive answer I took a punt and bought a
reel of RS 7481958.

It's about the same diameter (3.1mm) as cheap audio co-ax and has a
conductive layer with drain cable, so nice and easy to fit connectors to.

And it does the job perfectly. No buzz at all.

Oh - a 100 metre reel cost less than many a single posh name phono cable.
;-)

--
*I know a guy who's addicted to brake fluid. He says he can stop any time.*

Dave Plowman London SW
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