I don't think how we used this plugin is possible in OBS Studio
It allowed us to have audio sources separate from the video capture device allowing multiple video devices on each scene but only a specific audio input, I
https://youtu.be/lmnTTarnwLQ?t=4m17s
This video as an example, the larger video capture has the audio included using your plugin, when we switch scene to switch the video sources the new scene has your plugin using the other capture devices audio allowing that to be heard instead.
I've not found anyway of replicating this in the newer OBS Studio as audio levels are not specific per scene. :(