I remember reading a similar test, which was purposefully done sighted. There was a switch box, designed to have the most seamless, inaudible switching between two different components (don't recall if it was amps, pre-amps, transports, or what ever). There was some pieces of music playing continuously, and the testers could request the the switch be flipped at any time to change between pieces of gear.
After a few flips, the listeners began to agree that component B definitely was an improvement over A. All the usual adjectives were thrown out, sweeter, more spacious, increased depth, chocolaty, etc. So it was obvious that there was some difference between these two units.
Then the reveal was made. The reason the switch box could perform so inaudibly, is that the second component's wires didn't go anywhere, the switch was connected to nothing, and the first component's wires just looped back out of the box. So the differences they were hearing were completely in their mind.
