It is funny how that circle keeps going around and around.... (Although I'm not sure where it exactly started this time.) 1) You pointed out how a null test will demonstrate even the tiniest differences... I agree entirely, however, as I pointed out, if you null two of anything carefully enough, you always fine a little difference... So, rather than prove "two things are actually identical"... We always end up back at "now that we know exactly what the difference is we have to decide whether it counts or not". At which point someone chimes back in with that mystical knowledge that a certain null is "good enough we can act as if it's inaudible without bothering to test it". (I suspect you're right, and that some difference is "small enough to be inaudible", but I'm not quite sure exactly where that number lies... maybe we need to test it.) (And I think that's even more true with digital systems - where you can have extremely large measured differences that only occur for very brief amounts of time.) 2) I do apologize for #2. I personally am willing to accept that the results from those particular tests were what you say. (But a lot of other folks on this forum seem to think that "all claims are anecdotal if we don't get the data that goes with them".) And, yes, those results are interesting... especially that they show that, at least under those conditions, experience seems to be more significant that "raw hearing acuity". (But we still don't actually know if the massive difference in the hearing acuity of a five year old would override that difference - until we test it.) 3) That's good... and eliminates one possible issue with the results that many others seem to overlook. (Like the tests that only include the rather narrow demographic of members of some particular "audiophile group".) 4) Perhaps "common sense" was a poor choice of words. When we design a test that is intended to "prove a general case".... The general advice is to include any and all test samples that may reasonably be expected to prove the case. Since a single outlier renders you unable to make a generalization about "everyone" you have to try as hard as you can to find all the outliers. This is always a balance between practicality and thoroughness... and always ends up excluding a few that "everyone agrees won't matter"... This is a flaw that is present in all tests and is, for all practical purposes, unavoidable. I would, however, point out that it is much more of an issue in some situations that others. For example, there is a lot of incentive provided for fast human runners to come forward. The possibility of an Olympic gold medal, and a few $million in endorsements, makes it extremely likely that most fast runners HAVE been clocked. Even further, anyone who exhibited unusual aptitude in school has a good chance of receiving additional training to achieve their maximum potential. However, there is no such clear-cut incentive for people with exceptional hearing to come forward and be tested. Therefore, in practical terms, only a tiny percentage of every human on Earth has even had their hearing tested. (At a wild guess... very few five year olds, with their excellent hearing acuity, has ever gone to a course to train them how to listen properly.) 5) On the last part of your last comment... I very much doubt we have many five year old customers... (And, to be honest, I doubt many of our customers would buy equipment just because their five year old child preferred the way it sounds.) However, as has been pointed out so often, this is not a forum about marketing... but about science. Whether, if five year olds could hear a difference, there would be any commercial value to that fact is a matter for another forum. I'm merely curious, for scientific purposes, whether it may happen to be true or not.