So, I ordered and received my new WiiM Ultra early, in the end.
I have tested it all weekend, and here are my initial impressions:
Comparing the WiiM with the Node 2i, paired with my RMS DAC, using Coax for both, I can't say that I notice any difference, in terms of overall sound quality, or sound stage, even though, my initial comment from the first quick comparison, would have been that the Node was slightly better to my ears.
After repeating the same track various times (Radiohead - Weird fishes), switching from one streamer to the other, I wasn't sure any more, so in the end, I would say that I can't spot any difference between the two.
Removing the DAC however, purely for testing purposes, I can say that the Node is a slightly more obvious winner, with a warmer sound, and more open sound stage, compared with the WiiM, in my opinion.
Those differences, however, are subtle, in my opinion.
Now, where things get interesting: I was able to use the USB output from the WiiM, and connect it to the DAC, instead of the Coax, and there, I have the best configuration of all, for my equipment, at least.
With this setup, the differences are more noticeable:
The overall sound is warmer, cleaner and more dynamic, with a better definition in space (sound stage).
Big thanks to
@Witterings for pointing out the benefits of using the USB connection, to use the DAC clock, instead of the WiiM internal one!
I wasn't aware of this, and probably wouldn't have found out about this on my own...