Background white static noise even with microphones muted

AkroMenToSI'm not sure what this could be since it does work with other services on your PC, but I know that Teams does use some cloud based audio algorithms to help audio with all participants which is why they stress certified devices.  This is why they have the link to the certified audio devices here.

You might be having something with your DAC that is battling what is happening in the cloud.  Partners go through a lot of testing for their solutions to be certified because there are some things that need to happen to make sure everyone has a quality experience on the calls and all audio devices need to adhere to the testing put forth by Microsoft.  Maybe try a certified device on your PC just as a test to see if the issue goes away just as a test.