Not wanting to whip a dead horse, but I didn’t see anyone mention the fact that some streamers have better clock chips than others, so a bit less jitter is always a good thing, even if it borders on the inaudible.
The other issue is to make sure if you are feeding a DAC from a streamer, and if the clock chip in your DAC is better, that it is doing the driving and not the clock in the streamer. i.e. Use whichever provides the less jitter. Sometimes in order to get that to work you have to use USB or another input. Or even a DDC. As @jji666 states, experiment to see what sounds best to you.
We can hope that more expensive streamers use better clock chips and provide "cleaner" output, but YMMV.
Regarding WiiM, they have been very good about upgrading software based on user feedback, far more than some "high end" streamer companies. They know the Ultra had some issues at rollout and are working on them. At least they aren’t Sonos. LOL.
I’ve compared their O/S with that of a friend’s Bluesound Node 2, and I find WiiM’s just as good if not better. [I don’t use Roon].
Software bugs are one reason I generally wait about 6 months before jumping on any new device. Manufacturing quality also generally gets better over time as changes are made in the assembly line process. I plan on buying one around Christmas to feed an external DAC via USB, hoping by then most software bugs will be worked out.
I have three of their cheaper products feeding "cheap but better" external DACs (Schiit Modi) in a few systems (garage, outbuilding, and bedroom) and for the most part I have had no problems using them over the last couple years. I’m using Android and Windows PCs. I have no idea how well they play with iOS or Macs.
Are all streamers the same?
Dogma says they’re all the same. Experience suggests otherwise. Price may or may not be guide. Are there solid tech reasons such as bleed of noise into the digital signal? What does “it’s all about the ‘implementation’”really mean? How come power cords and interconnects make a difference? For example, there are numerous USB cords that separate the power from the signal cables to minimize interference and noise transference.
Why don’t we have an accepted science of audio, as yet? Where’s the research compilation esp at textbook level? Yes I’m happy just listening and using my ears and my biases to make judgments; no problem.
Yet I continue to see dogma, from the USA and Europe, indeed everywhere, that remains steadfast in their disbelief in variances. It becomes tiresome at times. But hey what do I care? Lol, my pursuit of fidelity and knowledge remain equally strong.