After needing getting to a point of upgrading my main rigs to a ultrawide screen and going between PC and Mac I came into the strange need to have a way to switch the 3.5mm audio out to run into my desktop speakers. I tried using the speaker/audio out from my monitor as the displayport signal carries audio as well but it was incredibly noisy and introduced a lot of hum.
So this is just a short post on how I made a small box to handle the switching. It’s just housed in a small black plastic box from Jaycar with a ground loop isolation unit inside, a couple of 3.5mm jacks and a DPDT toggle switch. The isolation box helps remove any hum introduced by the power of each device in the chain as the MacbookPro power supply tends to introduce ground loops for some reason. For wiring, I just used the cable from the isolator itself as there was plenty left over.