This is a very simple audio filter plugin for OBS Studio which reduces noise by downmixing a stereo channel to a mono channel via difference. Noise which occurs on both channels (e.g. due to mains loops or inadequate shielding of the cables) will be cancelled.

This is largely cargo-culted, so I make no guarantees that it will work for you.

sudo apt-get install libobs-dev

git clone https://github.com/pjt33/obs-flip-sum-filter.git
mkdir obs-flip-sum-filter/build
cd obs-flip-sum-filter/build
cmake ..
make
mkdir -p ~/.config/obs-studio/plugins/obs-flip-sum-filter/bin/64bit/
cp obs-flip-sum-filter.so ~/.config/obs-studio/plugins/obs-flip-sum-filter/bin/64bit/