If someone cannot hear on the spot the huge difference in timbre between these three cellos,then it very possible that he at least need EQ. for sure to optimize his system but more probably a new headphone or improving his system and improving acoustic in the room...And for the test the listener not only must hear differences but identifying why the no1-2-3 are better in the micro tonal playing dynamis on the spot too...
EQ help to optimize and compensate for some aspects of our system limitations yes, but it will not give by his own power a completely natural timbre perception if the system is not right to begin with or almost right or if the room acoustic is not well done or at least not bad even if there is no acoustic treatment... And the recording cd or files to take the test must be minimally good for sure as our friend stuartk pointed out...