SOLVED: Old thread, but leaving this solution here for anyone else who needs it...
Following this (check "Listen to this Device" for the Helix / Stomp deep in the classic Windows Sound Control panel) worked for me.
I can now have my gear (Bass Guitar and Moog Subsequent 25) both running into my Stomp on separate paths (as per this).
Sound from the Stomp is input to Windows 11 laptop via USB
Sound from the Stomp and whatever source I'm jamming to (from the Stomp plus YT/Spotify) is output from laptop via an audio interface connected to M-Audio 2.1 monitors.
That way, I don't have to mess with my PC sound config, whether my Stomp is connected or not.
I hook the Stomp up by USB and it adds in my instrument monitoring
Perfect