Other people have recommended this device that might work better for your equipment than the Fifine
With this device you shouldn't need anything else.
Although I don't recommend using your soundbar to sing through. It's not designed to handle the peaks generated when singing.
https://www.techlifegeek.com/2016/12/how-to-setup-karaoke-at-home-using-youtube/
https://www.karaoke-tutor.com/karaoke-at-home/index.html
https://www.howtokaraoke.com/everything-you-need-for-a-karaoke-setup/