Sound blaster z spdif INPUT as 5.1 dd/dts?

[fluxcapacitormb]

So the title vaguely says what I’m trying to achieve...I want the optical INPUT on my sound blaster z to accept an spdif signal from my tv’s pass thru? I have a roku stick that supports 5.1 did/dts pass thru, the tv supports pass thru bit streaming. But when I select digital in as my default recording device, there is no option for it to be 6 channel?! It only supports 2 channel stereo audio?! Stupid. Very. Up mixing the audio to 5.1 via sb pro studio sounds like poop. Is there any way to get the card to accept spdif in via optical? Or am I just screwed and need either the Logitech z906 (for it’s digital inputs and did/dts capabilities) or a home theater receiver?
This is all windows 10 up to date as of this posting w the newest sb z driver from late late year.
Thanks for any help.