Quite agree with point made by JoetheArachnid, if the test is sighted then I believe it has dubious validity. This is a highly contentious area discussed by Douglas Self among others.
I was at the Bristol Show in April, took in a few demos, (spent some time listening to the Senny HD700 which I liked.) However, back to the point, I sat in a fascinating demo by Nordost.
Differences between cables and mains distribution/conditioners were apparent.
In many of these demos the audience is told what the improvements will be and sure enough is amazed to hear said improvement. I believe there is an element of skilful salesmanship and applied psychology at work.
P.S Thank you smial1966 for getting this meet going. I was hoping another one would be arranged, I enjoyed the day in London last year.
I could bring Arcam CD36, Arcam rDAC, one or two of my DIY amps and HD650 and LCD2. My amps are the same as last year but changes made to interconnects and mains cables have improved the music for me.