On the macOS version (and I assume it’s similar on the Windows version), you need to use the “Stop” (square) button in Audirvana+'s transport controls rather than “Pause”, otherwise it will hold on to the DAC connection (in the default “Exclusive” mode).
You can disable that behavior, by turning off Exclusive mode (under Preferences | Audio System) - but that defeats some of the point of using Audirvana+ in the first place - which, among other things, bypasses the Core Audio (or Windows) mixer - simplifying the replay stack.
And, of course, a player running in Exclusive mode means that nothing else can use the DAC when it is playing - as that’s the point of it.
The TIDAL client on macOS has a setting for this as well (Spotify doesn’t, of course, as it won’t even let you choose an output device, much less how you use it …).
You should have no issues having multiple TIDAL clients (Audirvana+, TIDAL, Roon) up and running at the same time. Just only one can be playing.
Just to make sure, I fired up Audirvana+ and TIDAL, verified that both are setup for “Exclusive” mode, and then played a TIDAL track in Audirvana+. I stopped that, then played a track via the TIDAL client. Then I stopped TIDAL and went back to playing the same TIDAL track in Audivarna+, and it works just fine. I could swap back and forwards as much as I wanted, with both applications running, as long as I stopped playback in the one that was playing first.
Hope that helps!