When you use OBS Studio, you may meet the OBS not picking up desktop audio issue.
If you want to get rid of it, this post is what you need.
This post formMiniToolprovides some feasible and useful methods.

OBS is free and open-source software for video recording and live streaming.
Now, lets see how to fix the OBS studio not picking up desktop audio issue.
Also see:How to Download/Install/Use OBS Virtual Camera?

Here Ia a Guide!
Step 2: ExpandSound, video and game controllersin the list.
Right-clickRealtek High Definition Audio, and clickUninstall gadget.
Step 3: ClickDelete the driver software for this deviceoption and click theUninstallbutton.
Step 4: Then you could click theActiontab and clickScan for hardware changes.
Windows will automatically scan and download the Realtek HD Audio driver and reinstall the Realtek HD Audio Manager software.
If not, try the next solution.
Step 1: Right-click theSoundicon and clicktheSound Control Paneloption in parameters.
Step 2: Select Speakers on thePlaybacktab.
Then, select theSet Defaultoption.
Step 3: Click theApplybutton.
Now, you could test whether the OBS not picking up desktop audio issue still appears.
Thus, its recommended to uninstall Nahimic.
Now, the OBS not picking up desktop audio issue should be fixed.
Final Words
Is OBS not picking up desktop audio?
It is easy to fix this issue if you follow these solutions mentioned above.
I hope this post is helpful to you.
Just have a try.