Audio upgrade help (gaming/streaming)

Hello I am planning on upgrading my audio for my pc gaming setup and have done some research and had an idea of what o was going to buy but now I am wondering if it is over kill or will even work. (Also am planning on getting into streaming here shortly that is why I picked some of the things I have)

I do know that I am planning on buying the sennheiser hd598s as my headphones and the audio technica at2020 mic with the behringer 802 premium mixer or the xenyx502 mixer. What I was planning on also getting was a Dax/amp for the headphones the schiit mango and modi to be specific because I want clean audio which I don't have now. The question is do I need the sac/amp combo or Will the mixer provide the clean audio that I am looking for because I don't want to be hearing the constant buzzing/static that I am getting now when I upgrade.

Any help would be appreciated and if there is any better alternatives please let me know. Thanks.

Behringer makes pretty shitty stuff...
I would recommend this mixer instead.

The Dac looks nice! I don't see a mango, did you mean the Magni? You don't need an amp if you plan on just plugging your headphones into the mixer.

Btw, to REALLY isolate the electrical noise of your computer from the mixer / mic, use a power conditioner for just the audio gear. (don't plug your pc into the conditioner, that would defeat the purpose)

If you never plan on expanding past a simple streaming setup, here's a great all-in-one solution.

It has the capture input for a normal microphone (no need for a usb-mic), the dac, clean audio quality, and will power your headphones.

Also, you don't need a mixer since it has all the monitor output options for feeding your microphone back into your headphones without any latency.