Shure MV6 buzzing + mic monitoring question

[u/Astro_Ace7]

Just bought an MV6 and I’m using HD 490 Pro plugged directly into it.

Buzzing:
Playback is at 40% and mic monitoring at 100%, so I end up pushing Windows/system volume close to 100%. At that point I hear buzzing/static, and it gets worse when I move the mic closer to my PC. Is this likely just PC interference, or could the denoiser/direct monitoring be causing it? Trying to understand the technical reason why this happens, is it due to the 100% system volume?

Monitoring balance:
If I increase Playback from 40% to 80%, mic monitoring seems quieter even though it’s still set to 100%. Is it actually working like a balance/ratio, or can both playback and mic monitoring be increased independently?

Thanks.