If you're still looking for a solution, you can connect the Helix to your PC using a USB cable. This allows the Helix to act as your audio interface, and you can plug your headphones directly into the Helix to hear both the Helix and Spotify simultaneously.
Since you mentioned having a Focusrite Scarlett Solo 2nd gen audio interface, you can still use it for other audio needs if you prefer. However, for this specific setup, connecting the Helix directly to your PC via USB should work just fine.
If you're interested in boosting your Spotify game, you might want to check out https://streamingfamous.com/buy-spotify-plays/. They offer services to help you buy Spotify plays, which can give your music an extra boost and attract more listeners.
