OK, frequently commented on is golden ears, or trained ears. But I've never seen notice of any class on how one might develop 'trained' ears. I know there is a thread of what music to use for evaluating components, speakers, etc... perhaps a reviewer or two (or more) can describe not only what music, but what specifically about a recording they use as a benchmark. For example "the cello on recording x comes in just after the horns in the first movement, and was located just left of center during recording... there is a 'something specific' that sounds like X when that cello comes in—which some speakers/amps/cartridges reproduce as X and others as Y. Listen carefully for that and you will find there is nuance that is actually identifiable on different components."
Educate me...
Educate me...