Ok upgraded to v5 Desktop and testing with RPi4 NAA for HQP input, it works very very well.
When I’m at my desktop I actually prefer using Tidal Desktop this way vs Tidal Connect to WiiM Mini because Tidal Connect doesn’t support ‘auto play’ at all
I find that to be a useful for discovering music similar to recently played.
I changed between 44.1k and 48k based tracks alternating and no issues with garbled sound - but I was practical about it, letting 5 seconds pass before changing.
I don’t hate any track enough to need to change < 5 seconds 
Maybe faster changes cause it?
So far, very reliable.
RPi4 is happily powered by USB 3.0 port of my Mac which is also sending the Tidal Desktop data, single cable only required - I don’t need a powered USB hub
Will try iPad later (with Apple adapter of course)