I completely agree.
The definition of a "blind test" is unequivocal. It means the subjects do NOT know which amp, speaker, or whatever is being studied, whether it is drug studies in hospitals or amp studies or speaker studies. The subjects do NOT know. PERIOD.
Double-blinded test means BOTH the subjects and the administrators do NOT know. Only the persons preparing the tests know. For example, In a drug DBT, this would be the pharmacist preparing the drugs (that's me
).
Single-blinded test means only the subjects do NOT know.
When it
SHOULD be used is equivocal. In audio, if it is for casual listening or social gathering, you usually don't do blinded testing, especially DOUBLE-BLINDED testing.
But if you want it to be taken SERIOUSLY for PUBLICATION for the whole world to see and you want people like Toole, Linkwitz, and all the major audio respected and published experts to take interest and use your studies as REFERENCE, then yes, you SHOULD do at least valid single-blinded studies.
There is this thing call "human bias" and unless you are gods almighty, you will not escape it regardless of your status in life.
But sure, for Summer shindig and sweet soirée, you probably "shouldn't" perform double-blinded tests.