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.