Thanks for the reply...I guess the different sampling rate isn't a thing for other users...

Higher sample rates require more bandwidth; 2 of the 8 ADAT channels are used for double speed and 4 for quad speed.

With your 4 ADAT ports, this means for ADAT protocol:
- single speed: 4x8=32 channels, ADAT1-8, 9-16, 17-24, 25-32
- double speed: 4x4=16 channels, ADAT1-4, 5-8, 9-12, 13-16
- quad speed: 4x2=8 channels, ADAT1-2, 3-4, 5-6, 7-8

When switching to SPDIF only the first two channels of an ADAT port can be used
because SPDIF protocol by definition supports 2 channels, regardless of the sample rate being used:
- single speed: ADAT1/2, 9/10, 17/18, 25/26
- double speed: ADAT1/2, 5/6, 9/10, 13/14
- quad speed: ADAT1/2, 3/4, 5/6, 7/8

An easy solution to cover sample rate changes for SPDIF has been posted by MC a few minutes ago in previous post (#4).
Otherwise, for ADAT, you have to provide the routing as needed because the number of channels changes with single, double, quad speed.

Following this thread out of pure interest.
yys310, I don’t understand what protocol do you use? Is it ADAT or SPDIF?

But then you have a maximum of eight output channels in total anyway, two per each toslink port, regardless to the sample rate!

I do have a Digiface USB myself, but I can’t check it at the moment because I’m not at home: how do software playback and hardware output channels in Totalmix behave when switching from ADAT to SPDIF?  Are there still all of the 32 channels visible (at 44.1 or 48 kHz)?

I see…
So your idea in post 6 (after MC's suggestion) is surely the best solution.

Yes, loading different routings for the three sample rate ranges would be easy too.

NOT when you're running at 176.4/192kHz sampling rate.

Maybe I get you wrong. But to my understanding that would be incredibly confusing regarding the channel numbers. As it is now, the four optical output ports can be switched individually between ADAT and SPDIF. There is no overall SPDIF mode. So when I switch only the second port to SPDIF for example, the ADAT channels on port 3 stay nr. 17-24 and on port 4 nr. 25-32 at single speed.

I'm not sure how unusual this use case is anymore. At least, that is exactly what I am trying to do :-)

As more and more devices in our audio chain (home office / home stereo) become digital, many of us would love to use a Digiface USB or similar products to integrate between our range of S/PDIF source devices and our S/PDIF playback devices (e.g., DACs, Active Speakers, Headphone Amps). In such use case, ADAT is never in scope.

Of course, I'm also part of the cross-over market who has grown to love our RME-based product(s); but I also know that my use case is outside of RME's core focus.

Obviously that situation varies by context, and is a very important factor in your case where precise clock synchronization is critical for coherence.

But it becomes irrelevant in the context when the input streams and output streams are fully autonomous.

In my case, I have several input sources that I want to have always active, and thus I want to mix these autonomous streams together in the digital realm (rather than via an analog mixer). For example: home PC, WiiM Pro network streamer, CD/DVD, and a turntable (Waxwing). I don't care one bit whether the "phone ringing" from my PC alerting me that I have an incoming Teams call is even remotely synchronized with the song Roundabout by Yes that is currently playing on my WiiM Pro.

Likewise I don't care if the DSP'ed output going to my headphone DAC/amp next to my comfy chair is precisely synchronized with the DSP'ed output being routed to the active speakers sitting on my work desk. What I do want is the matrix mixing & routing flexibility so that I can easily switch from sitting in my comfy chair to jumping onto a work call in seconds without having to do anything other than pausing the WiiM Pro. (And then after the call is done, I just resume playing the WiiM Pro to continue listening to Roundabout at my desk as I work on the tasks that came out of the call.)

Again, this is only to highlight how the power of Digiface USB's mixing & routing could potentially be used in an environment that is all S/PDIF input and output devices, with no need for ADAT at all (and not even any need for time-alignment between the autonomous audio streams).