So, if listening to a piece on one set of equipment and then listening to it again on different equipment (A/B testing) doesn't work then how do Meridian test "improvements" to their equipment during its development? How do they compare their offering with competitors?
For those of us who are "believers" that A/B testing is not the way to go, the normal practice is to listen to a piece of equipment or format or whatever you are evaluating for an extended time, and then switching later.
For my purposes, I find that emotional involvement has been the best question I ask myself when doing evaluative listening.
Your mileage may vary.