Pabelson:
you have to invent and carry out some sort of blind test
You got it... A long term test...
How do you know you're not imagining a difference
You can measure differences (how about 0.25% difference?) in THD between the two and still won't be able to tell the difference in a conventional DBT with one minute clips. What do you think?!
The answer is, you don't know, and you can't know unless you compare them blind
So, when (not if!) you fail the above test you will sell your main gear and listen to a boombox for the rest of your life, just because you arbitrarily decided that "you can't know unless you compare them blind"? The emphasis is on arbitrary, until I see a conclusive research that shows consistent statistical correlation of DBT to sonic perception.
Without that, you are making an arbitrary decision that the particular method is a good indicator. I'm looking for the science here.
Go back and look at the roots of scientific evaluation. Even Einstein's theory of relativity had to wait many years for "official" proof, until someone could measure the effects of gravity on light. We tend to simplify and take things for granted, but that is not scientific. What's scientific is for one to ask why isn't reality in agreement with Newtonian mechanics and dare say that the speed of light is constant, risking ridicule by his colleagues.
You can ignore what your brain tells you based on what seems to be an incomplete or insufficient test data. That is not science, even though it includes scientific methods. I'm sorry that I don't know the answer, but I do know what to ask. You don't!
You seem to accept it that someone with X years in the audio industry "gotta know" more than what your own ears tell you. With that approach we wouldn't have an atom (which nobody could see at the turn of the twentieth century!) and would be still teaching Greek geometry instead of Calculus in our schools (Newton was "blamed" to be insane with his definition of infinitesimals...)
Dare to question!