Hi,
I have the SOtM SMS-200 Ultra. Setup is thru a web-based GUI called Eunhasu. Not being a techy myself, I found initial setup to be a pain and required some outside advise and some web research. Thankfully, once setup and fine tuned (I had stuttering that required changing some settings), you don't have to go back to it.
Roon is not necessary but is recommended if you have a Tidal or Qobuz subscription. You can set the SOtM to play music from Spotify or your local music folders, or even a USB stick plugged on the SOtM itself.
Which DAC depends on your budget. I hear a lot of good things about Chi-Fi DACs but the best ones appear to be those from Denafrips and Holo Audio.