Mine was doing the same with PC audio and Console Audio combined via the Astro A40 Mixamp. I never fixed it but I did read an article that said if one device was plugged in to one wall outlet, while the other device was plugged in to another outlet, this issue could happen.
which was exactly how mine was setup, Console and Mixamp to outlet #1 while PC / aux cord from PC to outlet #2
Never tried setting it back up with all devices only getting power from one outlet, if you can, that may fix it. Also read that low quality 3.5mm connectors could cause this. I did try buying some "higher quality" ones from Amazon, but it did not fix my issue.