Do mains cables make a difference??

[Marco]

I have found that anything with a switch mode power supply seems to have much less improvement from an upgrade cable. I would say pretty much immune.

Yup, but also rather crucially, that anything with SMPS [routers, Sky boxes, phone chargers, computers, smart meters, etc], sharing the same mains supply with other equipment, not fitted with with such, necessitates the use of something, filter or otherwise, to combat the amount of crap that they inject into said supply!

That's why I have a dedicated radial circuit installed for my hi-fi system, isolating it as far as possible from all that shit, and use screened mains cables, properly designed for hi-fi purposes, not glorified 'licorice sticks' posing as such

Marco.