Cabling an Audio Patchbay / Rack and Some Tests with Summing and Phase-Reverse

I'm completing and extending a Ghielmetti audio patchbay, showing some of the process. Also trying to move around the API system 500 modules (without luck, as the host seems to have an issue with powering the first slot). Some tests with routing signals and creating a difference signal by way of adding a phase-reversed variant. Sorry about the sound quality, I should find a way to get an external mic into the action camera :( If you find anything of this useful, nonetheless, let me know in the comments.