Tbg: The main question of your post seems to be, Do objectivists like Arny Krueger extol blind tests only because they like the results? The short answer is no. Arny K. and his ilk did not invent blind tests as a weapon to use against the high-end industry. In fact, they did not invent blind tests at all. Blind listening tests were developed much earlier by perceptual psychologists, and they are the basis for a huge proportion of what we know about human hearing perception (what frequencies we can hear, how quiet a sound we can hear, how masking works to hide some sounds when we hear others, etc.). Blind tests aren’t the only source of our knowledge about those things, but they are an essential part of the research base in the field.
Folks in the audio field, like Arny, started using blind tests because of a paradox: Measurements suggested that many components should be sonically indistinguishable, and yet audio buffs claimed to be able to distinguish them. At the time, no one really knew what the results of those first blind tests would be. They might have confirmed the differences, which would have forced us to look more closely at what we were measuring, and to find some explanation for those confirmed differences. As it turned out, the blind tests confirmed what perceptual psychologists would have predicted: When two components measured differently enough, listeners could distinguish them in blind tests; when the measurements were more similar (typically, when neither measured above known thresholds of human perception), listeners could not distinguish them.
Do all blind tests result in a “no difference” conclusion? Of course not, and you’ve cited a couple of examples yourself. Your preamp test, for one. (Even hardcore objectivists agree that many preamps can sound different.) Arny’s PCABX amp tests, for another. (Note, however, that Arny typically gets these positive results by running the signal through an amp multiple times, in order to exaggerate the sonic signature of the amp; I don’t believe he gets positive results when he compares two decently made solid state amps directly, as most of us would do.)
Your comments on statistical significance and random samples miss an important point. If you want to know what an entire population can hear, then you must use a random sample of that population in your test. But that’s not what we want to know here. What we want to know here is, can anybody at all hear these differences? For that, all we need to is find a single test subject when can hear a difference consistently (i.e., with statistical significance). Find ANYBODY who can tell two amps apart 15 times out of 20 in a blind test (same-different, ABX, whatever), and I’ll agree that those two amps are sonically distinguishable.
Which leads to a final point. You say you are a scientist. In that case, you know that quibbling with other scientists’ evidence does not advance the field one iota. What advances the field is producing your own evidence—evidence that meets the test of reliability and repeatability, something a sighted listening comparison can never do. That’s why objectivists are always asking, Where’s your evidence? It’s not about who’s right. It’s about getting at better understanding. If you have some real evidence, then you will add to our knowledge.