O, Lord, what have I started now...
From where I sit, at the time of writing, the earth appears to be relatively flat - as it has done for most of my life. This is a subjective observation.
However, since I am open to information and opinions from other sources, I actually think that there is good reason to believe that the earth is roughly spherical. This is an objective assessment based on the best available evidence now. But nothing is set in stone for all time - how can it be? "It is impossible to step into the same river twice" (Heraclitus).
Returning to the subject - of double blind tests - I do think that some people are missing the point. A double blind test measures what it sets out to measure. The results are true for that equipment, in that place, at that time, and for those people. Nothing more and nothing less.
No-one can accurately draw inferences regarding parameters which were not measured in that trial. Listening tests by individuals or groups cannot prove that, for example, cables do - or do not - add, distort or detract from the sound of other equipment in other circumstances.
However, I do think that the fact that the participants in double blind tests cannot be influenced by knowing the brand/model means that a double blind test must be more impartial than one in which they know what is being tested
Until there are more sensitive objective methods of measurement which cover the whole of an audio system from source to output, not just one component at a time, the choice of audio equipment can only be subjective. You pay your money and make your choice.