I can genuinely tell the difference between 320K MP3 and CD, and between CD and HD, (a group of enthusiasts got together and double-blind tested each other) but only in carefully controlled circumstances with a LOT of focus. As in, wearing really good headphones in a silent distraction-free room with my eyes closed and focusing on particular features like cymbals and chimes and staging, and even then only after switching back and forth between samples a dozen times. So after realizing that, I always aim to have CD quality, but I couldn't care less about HD audio. And like you said, $100 Craigslist systems from 1990 sound drastically better than modern consumer-grade systems. People started caring more about "smart" convenience features and less about sound quality a long time ago.