Mains cables and filters do we need expensive ones?

[wwm]

I have to admit to being a bit of a cynic when it comes to mains cables. If you consider the average uk home electrical supply first goes through a fuse then the meter followed by the distribution board/fusebox and then fed to the wall sockets by 2.5mm solid twin and earth, by using a 1 or 2 metre cable costing many times the amount spent on the internal wiring will suddenly improve the quality of the supply is for me unproven. I fell into the trap of installing a spur using 12mm quality cable and a good quality unswitched socket and Naim Powerlines. I did'nt hear any improvement and when I went from Naim to Devialet I swapped between the Naim Powerlines and the stock Devialet mains cable and again heard no discernable difference. Ok I am getting on a bit and my hearing isn't what it was but my son who is in the professional sound business said there was no improvement worth worrying about.