In reply to:
JOEMA: define “identified”.
They were unable to identify any difference whatsoever between two amplifiers in repeated blind tests. IOW take any two amp brands, fix all issues with DSP, volume, etc. Let the listener switch between them on his command, as much as he wants. He can listen to whatever music material he wants.
He doesn't have to identify particular sound qualities such as "bright", or "warm". His ONLY task is reliably identify ANY DIFFERENCE AT ALL that tells him which amp he's hearing, A or B. Out of of thousands of participants, nobody could do that. The challenge is still open.
Note: edited to reflect test is music only, not test tones.
