Check out this link: Audio Musings by Sean Olive: The Dishonesty of Sighted Listening Tests
I'm going out on a limb and suggesting that blind listening tests (when buying audio equipment) are unnecessary. It might even distort the reality you experience because our auditory memory is so short...
In Double Blind testing, is louder perceived as better?
I often read about the requirement for precise acoustic level matching when conducting double blind acoustic testing on audio equipment. Apparently, mis-matches in SPL are a variable which may permit human subjects to more readily...