Routing audio player output as backing track?

[Hartebee5t]

Is it possible to play an audio backing track as a source from Windows 10 to a JACK-based online session for others to jam with? I've been trying for hours to configure VLC under Windows 10 to select my JACK interface as its Audio Device for output, but so far only 'Default' and 'Speakers' are offered by VLC's dropdowns. Numerous forum posts refer to a 'vlc-jack-plugin' for this feature but that seems to be Linux only (or 'not Windows', at least). The Sounds settings pages in Windows only offer the same two source options as VLC.
Working from the JACK interface and looking back upstream towards the source, is it possible to select an audio source (E.g. VLC, YT or [coughs] pikaraoke) as Jamtrip's input feed, rather than the microphone or an external interface device?

[declension]

Maybe I've misunderstood (and haven't had time to try Jamtrip out yet, but it looks cool) but can't you just use Carla etc to route your Jack audio into Jamtrip's sinks as normal?

Then the challenge is just any Windows media player with Jack support (shameless plug: I added Jack support to Quodlibet recently) and then patch this in directly. Unless you want the backing track to appear as a separate participant, that's harder I guess