Make what use you want of it. Blind A-B testing can tell you if you prefer A to B. For whatever reason. Can it make you an expert on differentiating a 2db drop at 11kHz from a 5db spike at 19kHz? Not likely. Can it help you, combined with observing measurements, using great tools, to decide if that $10k set of cables and power conditioner is worth it? Probably. Hopefully. Can it make you wise to the tendency to fool yourself in quantifying the 'differences' you think you might have heard? Most definitely. So, without slicing and dicing, ad infinitum, I just keep it simple, and recognize the usefulness and efficacy of the 'science' involved, make my decisions, and get on with the enjoyment of the music I love, with the best system I can afford.
Why Do So Many Audiophiles Reject Blind Testing Of Audio Components?
Because it was scientifically proven to be useless more than 60 years ago.
A speech scientist by the name of Irwin Pollack have conducted an experiment in the early 1950s. In a blind ABX listening test, he asked people to distinguish minimal pairs of consonants (like “r” and “l”, or “t” and “p”).
He found out that listeners had no problem telling these consonants apart when they were played back immediately one after the other. But as he increased the pause between the playbacks, the listener’s ability to distinguish between them diminished. Once the time separating the sounds exceeded 10-15 milliseconds (approximately 1/100th of a second), people had a really hard time telling obviously different sounds apart. Their answers became statistically no better than a random guess.
If you are interested in the science of these things, here’s a nice summary:
Categorical and noncategorical modes of speech perception along the voicing continuum
Since then, the experiment was repeated many times (last major update in 2000, Reliability of a dichotic consonant-vowel pairs task using an ABX procedure.)
So reliably recognizing the difference between similar sounds in an ABX environment is impossible. 15ms playback gap, and the listener’s guess becomes no better than random. This happens because humans don't have any meaningful waveform memory. We cannot exactly recall the sound itself, and rely on various mental models for comparison. It takes time and effort to develop these models, thus making us really bad at playing "spot the sonic difference right now and here" game.
Also, please note that the experimenters were using the sounds of speech. Human ears have significantly better resolution and discrimination in the speech spectrum. If a comparison method is not working well with speech, it would not work at all with music.
So the “double blind testing” crowd is worshiping an ABX protocol that was scientifically proven more than 60 years ago to be completely unsuitable for telling similar sounds apart. And they insist all the other methods are “unscientific.”
The irony seems to be lost on them.
Why do so many audiophiles reject blind testing of audio components? - Quora