Hi,
WEISS only supports UPnP, or your use roon core to see the 50x as roon ready device.
Therefore you can’t use Spotify or Tidal Connect. Tidal & Qobuz can be used through the mconnect (app I don’t like).
I use Lumin U2 mini (+ ferrum hypsos exteran PSU) to stream through RCA to the Weiss, or if you wanna really get the best out of the DAC, use some dedicated music server like Antipodes, Grimm Audio MU1 or Innous.
Personally I’d highly recommend your move to Tidal or Qobuz, as Spotify doesn’t come close to that streaming quality.
Best rgds
Gerald