So far Ive just been using emulators, then opening them in OBS. So I havent been using a capture card.
Once I get my new computer setup I will be streaming PS4 using a elgato hd60.
Elgato has a capture card more for retro gaming (Game Capture HD) and there is a Retro Gaming Adapter (composite & S-video input to the card) for sale on the elgato website. I plan to get one of these Game Capture HD at some point. There is a compatibility list which shows the systems that the card supports, but turbo grafx isnt mentioned. I dont know if this is an oversight or not:
https://help.elgato.com/customer/por...re-hd-supports