For any FiiO X5III owners with the Meridian Explorer2 (ME2) DAC trying to use their X5 to stream Tidal with UAPP (v4.3.1): The latest X5III 1.21 firmware (which specifically claimed to enable USB Audio) for the X5 is now enabling me to smoothly stream Tidal Masters (MQA) and HiFi.
In previous X5 firmwares I had an issue where I got dropouts/DAC lights flickering while streaming. Now it's smooth sailing and I can stream and render Masters files in Tidal (blue lights, green lights, etc.) without any hiccups. Ditto for regular HiFI.
Note: In my case I had to go into UAPP USB tweak settings and click tweak #2 as I was getting errors and stuff wouldn't play sometimes. I'm not 100% sure that the tweak fixed it (could have been some other reason like getting other streaming glitches, etc. that were randomly happening self-resolved) but I've left it in place along with selecting bit perfect for the DAC. I'm really enjoying the results.
I have my X5 also stacked with a Cayin C5 portable amp (for extra power, bass boost option and a little easier to control the volume). Total stack is X5, C5 and ME2. A real handful!
The combo of the X5, C5 and ME2 is a smooth, sweet sound and, especially with MQA files (I stream a lot of the more recent ECM Masters stuff), a real silent background and very clean crisp highs and deep lows. I still get the occasional decoding error that stops playback but they're infrequent. In those cases I just go backwards and select another song or retry the previous one and it plays fine.
Update: I think these decoding errors are due to crappy WiFi connectivity when far from my router. As said, one of the The X5III's issues is its weak WiFi, especially if your router might be older and less advanced/robust. When closer to the router the playback is way more consistent.