Sorry to correct you, but it’s not like that.
A device with steadyclock (FS) uses it also internally. Otherwise it would be sort of a joke.
Having digital audio signals reaching a slaved RME interface, steadyclock (FS) can 'clean' it from jitter. As master device it sends out audio signals with the same accuracy.
I highly recommend to read this full article:
https://www.rme-audio.de/steadyclock-fs.html

The SteadyClock technology of RME's latest products guarantees an excellent performance in all clock modes. Its highly efficient jitter suppression refreshes and cleans up any clock signal, and provides the clock signal as reference clock at the word clock output. At the same time, analog conversion is performed on a guarateed level of highest quality, completely independent from the kind and quality of the used reference clock. The cleaned and jitter-freed clock signal can be used as reference clock in any application. And the quality of the external (input) clock doesn't matter anymore.

So .. in Pauls setup my understanding is ...

The UFX is clock slave to ADI-2 Pro and gets clock signal via AES IN.
SteadyClock on the UFX will perform a jitter suppression of the clock signal from the ADI-2 Pro FS which is already accurate due to FS clock. If there would be any clock jitter then SteadyClock (no FS here) would eliminate it.

So I think at this point SteadyClock will perform the jitter suppression based on his "normal" clock, which is "fine enough", but has no FS quality. Differences not audible, but measurable like with the ADI-2 Pro vs FS version.

This refreshed clock signal (by normal SteadyClock using the normal clock of the UFX) will be further propagated through any digital output of the UFX and the WC output.

This is my understanding.

So .. in theory it would be the same if UFX would become clock master.
And the ADI-2 Pro FS would perform after SteadyClock FS processing the D/A conversion by using its own FS clock.
All clock slaves getting clock from UFX via WC would get it in the quality of the clock from the UFX
- if UFX is slave of ADI-2 Pro clock signal is refreshed / jitter suppressed by SteadyClock using its own non-FS clock
- if UFX is master, then clock comes also from his own non-FS clock

This is my understanding, but I might be wrong :-)

Is an upgrade from UFX to UFX III (with FS clock) possible if this is your desire?

Although, remember the discussions about FS vs non-FS versions of ADI-2 Pro. There was something like a consensus, that FS clock doesn't deliver better sound. Some better measurement values.

Consider .. digital recording has already successfully been performed, when FS clocks were not yet available (or at the beginning too expensive to implement).

But as I mentioned, if this is of importance for you and be it "to be on the safe side", well then I would upgrade to UFX III.
You will definitively still get a good price for your UFX on used market to cross finance it.

Interesting points Ramses and yes the UFX iii would solve quite a few problems and simplify a few things for sure. I’m learning to relax about the clocking issue in general but still just trying to achieve the best performance with the gear I have.

I’ve never fully stated my whole digital setup in this thread so here it is at present.

Main Audio IO passing audio to/ from computer is Madiface USB connected to ADI 648 mostly running at 96Khz. This is then connected to 3 x Cranborne Audio 500Adat racks which are my main multichannel converters giving 24 analog in and out. The final 2 adat ports on the ADI 648 are connected to the previously mentioned UFX version 1 and I use it’s AES connections to feed in/ out the ADI-2 Pro FS R BE giving me a total of 32 IO and provides additional IO mainly for headphone mixes.

The UFX 3 is a decent simplification solution but I’m also tempted )dreaming) by whatever RME come up with to replace the PCIe HDSPe MADI FX. It’s way more channels that I would ever need but it’s FX - eq in particular is appealing for me to achieve some speaker tuning. I’m ultimately hoping RME will add more speaker calibration features like delays and more eq bands to Totalmix as I already have a 7.1.4 speaker system in addition to stereo that works well but getting it all tuned via various DSP stages in Logic and then in Totalmix does all I need but it’s more complex that I would like.