Is this audio setup for FPS gaming, or more for music?
Do you have speakers or studio monitor your planning on using with the PC?
If more for music, then get the Soundmagic HP200 headphones and the Schiit Fulla ($90, USB/DAC/amp).
If more for FPS gaming, then the HP200 headphones and a Sound blaster Z sound card.
An Audio interface, like the Scarlett Solo is like an external DAC/amp.
Which does not offer any headphone surround sound, like a sound card would.