There are hybrid SACD discs, that is, discs with both redbook and SACD tracks. Some SACD discs are 2 channel, some multi channel but which would play on a 2 channel system.

I played a hybrid SACD disc, Dvorak's New World Symphony - the NS999ES played in CD resolution. I tried to play the SACD Dark Side of the Moon, and no output at all.

Bummed.

Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.