TL;DR You play Rimworld, or use any Unity based programs/apps, do not mix it with Nahimic 2+ Audio Enhancer utility!(I uninstalled it)
Some days ago, when I started to play Rimworld, I noticed a very annoying problem in where the game would never produce any sounds, at all, and I made a post about it here too https://ludeon.com/forums/index.php?topic=43450.0 Where... no solution was found obviously. Rimworld's output log was always saying this specific line that caught my eye: "FMOD failed to initialize the output device, attempting to initialize the null output." It annoyed me a lot.
Several days passed by with no solution found on the internet either. Until now.
I use a MSI gv72vr 7rf gaming laptop, it came in with a preset installed utility called "Nahimic +2". This utility has received many positive reviews due to its sound enhancing capabilities especially suited for surround setups and stereo headsets, and this utility usually comes bundled in with the laptop's recommended Realtek HD audio driver.
What went wrong though? Well, As it happens, it seems that Nahimic 2+ and Unity(rimworld's game engine) Conflict with one another for domination of sound assets(or something like that), which causes malfunctions. In this case, Nahimic's influence was completely killing my Rimworld's output capability.
After a little bit of more research and finding out that Nahimic is not a necessary utility, I uninstalled it, both its Normal version and its VR version. Rebooted my laptop and, voila! Rimworld has sound.
Moral of the story. Do not use Nahimic 2+ when playing rimworld. In my case, I don't feel I need the features it offers, so I uninstalled it for good. I am posting this topic here to try and help those who are facing the same problem as I did. Please consider putting it as a sticky maybe? Because this problems seems to have been reported very, very few times. So few that maybe people gave up on trying to find a solution.
Thanks to OP. I got rid of Nahimic 2+ and I now have sound again. This is still a bug in May 2020. I bought the game in 2018 and put many hours into it. Strange thing is that Ive had no problem until a week ago. But its working now. Thanks again OP.