For me, Sebrof has hit the nail on the head here - the human ear/brain are still unsurpassed by any technology yet invented. One must develop one's ears to really hear and understand differences in pieces of equipment, and this requires ABA testing, otherwise one is metaphorically groping in the dark.
(I also disagree that Art Dudley has set up a straw man argument, I think both quoted points are logically sound.)
Mapman's advice on how to develop one's ear is good. Listen, listen, listen, to as many different pieces of music on as many different pieces of equipment as you can. This is also how we professional musicians learn.