Pretty much everything other than power cables makes more of a difference in HiFi, so it's one of the last things to look at IMO. For example, spending £50 or so on some well thought out decoupling of components / speakers will make far far more difference. I see a lot of systems where you could sell the expensive power leads & get something like a much better DAC, better speakers, better amps etc. Cables aren't going to 'improve' a system.
If you feel that a power cord can transform a system, then there should be no problem in doing a blind test.
Mana Acoustics Racks / Bright Star IsoNodes Decoupling >> Allo DigiOne Player >> Pedja Rogic's Audial Model S DAC + Pioneer PL-71 turntable / Vista Audio phono-1 mk II / Denon PCL-5 headshell / Reson Reca >> LFD DLS >> LFD PA2M (SE) >> Royd RR3s.