If people could not detect any differences between identically measuring cables in the double blind tests that have already been done, then that shows we can already measure everything about audio cables that is needed. Amazingly, directionality is not one of the things measured for. Which just goes to show it doesn't matter, if even exist!

Haaaaving said that, I'm not sure DBT are the be-all and end-all of testing. I'm sure some things are have a very small effect below 'perception' but over time can have an effect, even if they are subconscious. Just because we are not fully conscious of it does not mean we are not detecting it and it is not having some effect on us. So there we go I shot my own argument in the foot! But I do think that if an effect is worth serious consideration when buying a product that it would be detected in a DBT.