Loud buzz from speakers connected to L1T 2x2 KVM

I recently bought one of the 2 PC x 2 Monitor KVMs from the Level1Tech’s web store, and I’m trying to troubleshooting a loud buzz I am getting from one of the PCs.

I currently have audio from both PCs passing through the KVM via 3.5mm audio cables, then directly from the KVM into a set of speakers. There is a slight hum from one PC, but a much worse one from the other, and I’m at a loss for what is causing it.

Any ideas? There’s not much I can do software-wise (it’s a pretty locked down PC provided from the company I work for), but if it’s a matter of needing higher quality cables or better speakers then those are both doable.

Sorry but I have to try and ask of you have tried to reseat the 3.5mm plugs? It seems its not inserted well?

At the surface, it feels like a contact issue. Try to rotate the plug as well?

I’ve unplugged and replugged them all several times with no change

You might need a ground loop isolator or two.

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You got yourself a ground loop.
Could try running a cable between the PC-cases or plugging in all devices into the same power strip.

Or this

are the two computers plugged into different outlets, or on different breakers?