Soo...what's your audio problem? Just the fans being loud?
The projectors and the virtual camera are both silent. You need to run the sound a different way. If you need to get it from OBS to anywhere other than a direct stream or recording from OBS, then the only option is the Monitor, and there's only one of those. So you'll have to choose between using that for your headphones, or for the soundtrack to an external video send.
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Or, you could move ALL of your audio processing to an external tool. You might not necessarily need a full DAW or house-priced concert mixer, but that would certainly do it! Then, all of your sources would connect to that external tool, not to OBS, and you'd feed everything from that external tool, not from OBS. OBS *only* does the picture at that point, and the bare minimal sound that it absolutely has to, only because it has to.
If you have videos or other soundtracks that you can't move out of OBS easily, use OBS's Monitor to send them to the external tool. Don't stream or record them; see the next point.
If OBS needs to stream or record, then send it the finished soundtrack from the external tool, as OBS's only audio source for that purpose, with no processing whatsoever in OBS. Just a dumb passthrough. And don't Monitor that source in OBS; almost guaranteed feedback if you do!