Need help with spdif_o header

[ExXsTacYx]

Soooo I was wondering I had an extra toslink port and thought I should try and like put it on spdif_o. I had done a project a long time ago taking a ps2 apart. Leaving me with that extra part. I had soldered the wires to link up right and when I put on the header it shines the light through the optical cable and even gives me the digital audio output driver however I don’t get any sound whatsoever from it. I have the toslink cable to a Astro mixamp pro tr. when let’s say Spotify is playing through with digital output as the audio main it shows its playing just I can’t hear anything. Like you can see the audio bar thing moving like its playing something. If that makes any sense. Am I missing something? Like do you need a sound card for this ? No biggie if this won’t work