HDCD--where have I been? MP3 land, I guess. I had no idea about this until I noticed "HDCD" light up in Windows Media Player 9 yesterday. That prompted a search, leading me to
a Wikipedia page and that link above. I figured out how to enable the feature in WMP (24-bit playback), and I have a 24-bit Audigy 2, so all parts seem to be in place. I wish I could say more certainly that it makes a big difference, but without A-B'ing on good audio equipment, the placebo effect can't be ignored. I do think it makes a significant difference. It certainly does to my CPU, which seems to be twice as busy now playing that content.
So, an honest 20 bits of sample resolution from a format designed for 16. Available since '95? It really makes this old audiophile feel dumb. But the implications go beyond that:
Nobody cares. If this had any mindshare out there at all, I would have spotted it years ago. Everyone is complacent with the compressed little audio files they listen to with their cheap earbuds and laptop speakers. If the mass market doesn't care, it hardly makes an impact. What a shame.