I have a couple of Parasound CDP-2000 Ultra CD players (1998-99 vintage) that have HDCD decoding. As noted, the small audiophile label Reference Recordings, based in San Francisco, and all of whose recordings are engineered by the excellent "Professor" Keith O. Johnson, has presented most or all of their material in HDCD since 1992. If you don't know them, their catalog is mostly classical and jazz; many worthwhile titles, and their sound is usually superb. I'm looking right now at one of their CD's, "Testament: American Music for Male Chorus and Band," that reads on the label "The World's First HDCD, High Definition Compatible dDigital Recording." It was recorded 6/1992. (And Reference Recordings is supposed to be making a comeback from the dead, namely the bankruptcy of Dorian, and returning to life shortly, according to another recent thread here, so hopefully their catalog will become available again soon.)
I also have three wonderful (and great-sounding) bluegrass CD's from the same label, Acoustic Disc, all of which are HDCD. These are, in order of release, "Old and In the Way: That High Lonesome Sound" (ACD-19, released 1996), "Old and In the Way: Breakdown" (ACD-28, released 1997), and "Old and In the Gray" (ACD-51, released 2002). I assume there are a number of other titles in HDCD from this label.
I also have three wonderful (and great-sounding) bluegrass CD's from the same label, Acoustic Disc, all of which are HDCD. These are, in order of release, "Old and In the Way: That High Lonesome Sound" (ACD-19, released 1996), "Old and In the Way: Breakdown" (ACD-28, released 1997), and "Old and In the Gray" (ACD-51, released 2002). I assume there are a number of other titles in HDCD from this label.