Blind Listening Evaluation

Dekay: Fair question; no two units ever measure identically, for example. But barring construction flaws, units tend to measure within very tight tolerances. (Speakers can be an exception, but nobody ABX's speakers.) If so, and if they cannot be distinguished in an objective (e.g., ABX) test, they would qualify as "identical" in my book. And if a company were putting out a product that sounded different from unit to unit, why on earth would you buy it?

The primary use of objective blind tests (e.g., ABX) is to determine whether two units can be distinguished by sound alone. That's usually not the question consumers are concerned about, and besides, performing such a test correctly is not trivial. More informal blind A/B comparisons can eliminate biases about certain products or brands, but they don't eliminate all biases. (For example, you have a built-in bias toward assuming that any two units will sound different, which is why listeners sometimes insist that identical units sound different.) So while blind tests are a good idea, and could tell us a lot about our hearing and about the components we listen to, they aren't terribly practical or useful to individual consumers. (Audio salons, if they chose, could offer them, but they have profound economic reasons for not doing so.)