I use something similar to this for speedrunning sm64 and it looks okay

https://www.amazon.com/TKHIN-Microphone-Loop-Out-Streaming-Conference/dp/B098JKHGH9/ref=sr_1_4?crid=3FVHUO7WFAH66&keywords=hdmi+capture+with+audio+out&qid=1646844212&sprefix=hdmi+capture+with+audio+out%2Caps%2C129&sr=8-4

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Of note, lower end capture cards are going to have some mild color issues, but it can mostly be solved with filters in OBS if you are worried about that.