Real world intruding but a few years back, one friend of mine got into SACDs, HDCDs, 24bit/96KHz, 24bit/192KHz and quite a few other varieties of snake oil. He could easily afford the expense but in testing, none of us were able to tell a good CD from any of the "advanced" format CDs when listening over speakers and very few were able to agree on which format sounded better when using his headphone collection.
About 6 months back, he held a party and we tried the various tests from
Think You Have Golden Ears? Take These 10 Audio Challenges and Find Out. It seemed none of us had the "golden ears" required to hear the differences in the real world. Perhaps a few decades back but our old ears are not what they used to be.