Hello, still the owner of an older SB card, but curious: On the DE website, see
https://de.creative.com/p..., it can be seen from a picture of the card that the rear aperture is only labelled "Optical OUT". Likewise, in the "Technical Data" section it mentions, among other things, "...Input options (main unit)...1 optical TOSLINK output...". From my own experience, I can only say that
Creative Sound Blaster Z (PCI-E x1) has both an optical input and an optical output; perhaps that would be an alternative...