Exactly, in order to do the measuring you need equipment that almost no one has, therefore its expensive. Who has an ABX comparator sensitive enough to keep up with high end headphones?
Secondly you can feel sound that you can't hear, I don't know how people might process that. I don't know what happens to people kept waiting to do a test and are anxious or annoyed or tired, or what happens to their ears if they use 'phones, stop, start, stop start etc or change the order of tracks or change the order to cable changes.
I know that there are people that can hear beyond the normal range, and that music pros can detect things regular listeners would not in a live performance. I don't know what influence these people have priming others on what equipment sounds like.
Explain how to do these tests on a non-professional budget, and then do it.