Sounds interesting Gary
So you tried three separate cables? The ones that came with the equipment, the low loss coax cable and the Yello cable? I'm not clear why you introduced the coax cable.
Did you undertake the separate supply from your domestic unit yourself and how? Do you recall if this itself provided much 'positive improvement'? I've often wondered if I should ask my sparky to provide an additional new domestic (separate) unit and run from this to my listening room.
Current: [P20] Roon/Tidal > Custom PC> Chevron Paradox NDF16 > Phast Pre > Neuro. 686 > Tannoy Berkley (RFC tweaks)