^^^^ I mean that if you compress via MP3 a CD or track that is HDCD encoded, and then use the MP3 to burn a regular (WAV) CD and play it (on an HDCD capable player), it will read as HDCD-encoded. As I said, in every case you'd need a player capable of reading HDCDs to know. And as far as how much the benefits of HDCD are affected by the lossy compression, I have no idea. Never had any reason to try or care b/c I don't use MP3s for much. This is actually hearsay about MP3s, but I don't doubt it b/c I know for sure that it survives FLAC compression. I could try it some time, it would be interesting, but I'm pretty sure I know what I'll find: My HDCD light will go on, but it won't sound as good.
If this doesn't sound right to you, you're not alone. I was pleasantly shocked when a downloaded FLAC (of an unreleased album, Time Fades Away) read as HDCD in my player (even though I was already informed that it was supposed to be sourced from the HDCD-encoded master), and sounds like it has the sonic benefits of HDCD intact.
Here's something somewhat related that I found interesting: Once, when I ripped an HDCD disc to WAV for myself, I listened to the WAV for some reason via EAC. It had an almost skippy chopped up sound, as if it was reading all the info on the disc somehow consecutively instead of concurrently. I thought I had a bad rip, but when I realized that the disc was HDCD, I decided to try to burn it and listen. It came out fine (and HDCD-encoded). EAC seemed to be missing the part that tells the HDCD reading chip to kick it, but wasn't passing over the extra info the way a normal player would in that case, resulting in a strange, out of sequence playback. Why exactly this happened, I have no idea. I should also mention that if you copy an HDCD disc, it always comes out with the HDCD intact, since some people might even be wondering about that.