Good mic set-up?

So, I'm looking aty new headphones, new speakers and a nice mic set-up. I'm hopefully pairing something like some DT990's or AKG 702's with a Fiio E10k and something like Audioengine A2+ or Tannoy 502's for my speakers. Hoping to get an AT2020, but not sure what to get with it?

Behringer Xenyx 502 mixer?
Focusrite Scarlett Solo?
Or something else? Need a good audio interface/mixer for an AT2020 basically, looking to spend £100 at the absolute max, prefer to spend £50-£75 though.

Have you considered just getting a USB mic?
I have a Blue Yeti and have nothing but good experiences.