Did he test blind or sighted. If sighted he may well have been subject to confirmation bias, expectation bias etc.Check out this Audioholics review of what happened when they changed the crossover of a high end speaker to one using phase coherent FIR filters. Gene Dellasalla, the head of Audioholics, said he was skeptical that phase coherence based on papers he had read, but after listening to the difference as they switched back and forth he called FIR filters a "game changer", achieving "immediacy to the sound", "better imaging", and the "utmost accuracy and lifelike sound".
Ignore my opinion, watch the Audioholics 11:57 minute review here.
Do you think Gene Dellasalla was imagining things?
They used an expensive professional processor by Marani to do the FIR crossover filters, but the miniDSP Flex can do the same thing.
No-one is immune - it is how our brains work.