Playback Designs also has a streamer, the MPS – X. It’s role is similar to the Nagra in terms of accepting an ethernet stream and then converting it to an optical format.
Apparently even using it without the optical interface with other manufacturers’ components has benefits:
MPS-X + LampizatOr Pacific 2
In the last part of the test, I use Playback Designs MPS-X as a digital frontend for my LampizatOr Pacific 2 with JCAT XACT-S1 (see the review HERE) as the source of the signal. I connect the latter first directly to my DAC via USB and later connect the server to MPS-X also via USB and forward the signal to LampizatOr using KBL Sound Prism coaxial SPDIF cable. I play the excellent Renaud Garcia-Fons Trio’s „Arcoluz” (24/48 PCM) album. It sounds fantastic played by Pacific 2 alone. The sound is open, highly energetic, pure, transparent, resolving, but also smooth, naturally warm, and just incredibly enjoyable.
Now I make a switch – the USB cable connects XACT-S1 with MPS-X and the latter sends a signal to Pacific 2 via Prism coaxial cable. So there is one more cable and whole digital interface (coaxial) involved which complicates things and in many cases, it could negatively impact the sound quality. And yet, it is obvious immediately that the Playback Designs digital front end perfectly does its job. It’s like there is even more sound in the sound, as there is more essence to it, or to put it differently as if what comes from speakers becomes closer to a live performance. There is more energy in the sound, it is even more open, and it’s free as if there were some limiters there before that didn’t allow the sound to fully spread its wings.
https://hifiknights.com/reviews/sources/playback-designs-mpd-6-mps-x/
In my system, where I use Roon to stream Tidal and Qobuz, and to manage stored music files, I notice significant sonic differences between the sound of streamers (i.e., Roon endpoints), and little to no differences between servers running Roon Core.
I suggest the next curiosity for @tcutter is to demo a "nice" server in place of his Nucleus core, use the same connections, and let us know if he detects any differences.

