Fixing analog audio on the $2.58 HDMI-to-VGA adapter

I recently purchased an ultra-cheap HDMI-to-VGA DAC to hook up my Nintendo Switch to my CRT monitor and external speakers. Unfortunately its audio out jack produced serious noise problems on my audio mixer, as well as my PC's mic jack. I spent several days diagnosing impedance issues, prototyping filtering for the delta-sigma audio DAC, and reworking PCB components to produce the best quality audio achievable with the hardware.