Talking of a load of 100% bollox! ...
I've done blind A/B tests, I've even enlisted the help of a music loving, non hifi friend when I'm unsure if I'm hearing things. On one occasion this was to compare a standard mains lead with another EXACTLY the same except that the cores had been plaited (kimber style) She had no idea what was being changed & in fact her comment was "I don't know what you've done but that's definitely different... but I'm not sure if its better"
But I can see you've got a firmly help view & so nothing I or anyone else can say will change your mind. I'm astounded that you can't (don't want to) hear the difference between a "crappy old extension block" & one made with good quality cable & switch-less sockets... but your view must be saving you a fortune - lucky you