How can the measurementistas assume that every possible measurement has been discovered? Even with existing measurements, few agree on the actual tolerances or hearing limits into which the measurements and tolerances fit. It’s also rare that any reviewer mentions humidity, atmospheric pressure, what they ate during their last meal, the blood glucose levels, blood pressure, mood, medications or any other variable that could impact earing acuity.
In the late 1990s, I was personally involved in a test of two absolutely identical models of preamps. There was a three millibel difference in the otherwise dead flat frequency response. 3 MILLIBELS, NOT 3 DECIBELS! Four listeners were involved. We were consistently able to identify a difference and to say which unit was the "A" unit and which was the "B" unit. The difference didn’t jump out and grab us, it was more of a subtle hardness. But we all agreed that the unit without the hardness was the winner.
The manufacturer that hosted this test built all his equipment to a much closer tolerance because of the results of that test. It required special instrumentation, very clean electrical circuits feeding the equipment and a lot of patience and understanding of his circuit and the components used in his equipment. He still enjoys a reputation as to top designed and manufacturer.