@tomcarr , just some commentary which is off of OP's original topic, but I do remember reading about HDCD in Stereophile when it (HDCD) was a new thing, and I was intrigued. I was always thinking I should have ordered my Muse DAC with the HDCD chip which was an option back then. But I'd say HDCD must have fizzled? By most standards, I have A LOT of CDs, & HDCD was never a factor that caused me NOT to buy one. But with all these CDs, I can only off hand think of four that are HDCD and I probably own a few HDCDs that I am not thinking about, but not many.
But SACD, in my opinion, is a different animal. A good SACD (and admittedly, not all of them are, for example I am most disappointed with the Japanese SACDs I have bought) truly does, to my ears, sound a cut above everything else I have heard in my system. (But s I previously noted, I don't have vinyl.) I'd almost go as far as saying that, although some are better than others, I have not (yet) bought any of the MFSL crop of SACDs that have disappointed me.