One of my all-time favorites in this area was a review done many years ago by a upper midwest audiophile club.
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They did a listening test comparing a $300 Pioneer receiver with two $10,000 "audiophile" mono tube amplifiers.
At the beginning of the test, the listeners knew which device they were listening to and, predictably, the Pioneer receiver was painful to listen to, destroying the music.The mono amps were all that is wonderful in listening.
Then the identities were masked and the listening test was done again. Most of the listeners could not tell the two apart, guessing incorrectly about half the time.
A sad commentary on the industry when an audiophile club cannot even tell a $300 receiver from $20,000 of audiophile amplification.