I ended up with a roundabout use case for this feature. I’d like to use TIDAL’s app instead of Roon because TIDAL has way better music discovery than Roon[1]. I get lots of value from Roon’s transport, which as far as I’m concerned is the best in the industry, but Roon wants to be constrained by my library (I don’t want it to) and Roon’s app UX is nowhere near as thoughtful as TIDAL’s desktop app.
If Roon could work with audio from OS audio inputs, I’d route TIDAL into Soundflower (https://github.com/mattingalls/Soundflower), which appears as an OS audio input (imagine another microphone device), and tell Roon to play that input. Obviously I’d lose song-level playlist control via Roon, but I’m ceding a fair amount of song-level control to dynamic radio/dynamic playlists anyway, so on balance I think I’d accept that tradeoff.
Totally understand that this would be a lot of work relative to the benefit and also somewhat platform-specific, so it’s unlikely to happen. I’m just documenting the use case on the off chance a product manager sees this thread.
[1]: Specifically, TIDAL’s recommendations use a much wider set of music (all music, not just my library/the relatively small part of the musical world that I’ve heard and favorited), and TIDAL supports dynamic track and artist radio using that far larger library. More (any) ways to discover/play music not in my Roon library has more. Ideally, Roon would add great music discovery, but the lack of official response on that topic, Roon’s ongoing focus on a manually-curated library, and of course the complexity of discovery/recommendations make that seem unlikely.