I was not talking about audio differences. We all agree that ears make the final decision, and we can test everything we want with the unit. I was just curious about what goes behind the scenes, in terms of acoustic/physics (types of filters, routing in series/parallel, etc.). I think we can describe it with some objective terms. It does not replace the practical side of a recording session (set a mic with different positions/angles to hear the differences), it would be complementary for curious people.