We had such routing topics already in some other threads here on forum which you should be able by usign the search function of the forum or by using google using this pattern to limit the google search to the RME forum:

<search text> site:forum.rme-audio.de

Or look here, which contains some useful diagrams:
https://forum.rme-audio.de/search.php?a … 42&p=2

Its no problem to use outboard gear and to send audio through it as needed. Its simply a routing task.

In your case the AD/DA converter is external, so the channel names differ, "ADAT" x/y instead of "AN" x/y.
The routing part stays the same.

The key is here to use submix mode and what to send to the external device ...
In TM FX you select the HW output to which the external device is connected (ADAT "x" or "x/y", mono or stereo)
and then to create the required submix, which audio you want to send through this external device
by raising the faders of HW inputs and/or SW Playback channels (top and middle row).
HW inputs = inputs on the recording interface or external device
SW playback channels = audio from PC/Applications.

Don't become fooled by TM FX design.
If you send audio to an output then it is not directly sent to the real output on the device.
1st it appears in SW playback channels (kind of "virtual" output).
Then its under your control in TM FX which outputs shall get this audio stream (monitors, phones, etc).

TM FX also offers a simpler mode "DAW mode" where TM FX routing features are turned off.
But then you need to route everything in the DAW (then there are no SW playback channels).

If you want something like this in TM FX as an easier starting point, then you can simulate "DAW mode" in TM FX
by sending audio from SW Playback Channels to the corrensponding HW output.

Easiest such a routing can be performed in TM FX by using a predefined routing:
TM FX: Options -> Reset Mix -> Straight Playback

The usual sample rates are 44.1 and 48 kHz. You seem to have typos in your text which make it difficult to understand what exactly the situation is.

General advice: check your setup step by step.

Babyface seems to be or should be clock master.
Check / ensure in the RME driver settings that clock source is set to "internal".
On the Behringer ensure that settings are for clock slave, use clock from optical (ADAT).

Check the ADAT ports by loopback test with TOSLINK cable.
One the RME side you can look at the driver settings whether you get a connection.
Change / swap cables to validate both cables, not that one is defective.

Not sure whether this brings something visible on the Behringer side, possibly not.

Then check each transmission direction:
1. receiving direction:
Get a Mic, connect it to 1st ADA8200 port, enable 48V if required (condenser mic).
Do you see a signal on the ADA8200 ? Do you see a signal in TM FX port ADAT 1?
2. sending direction:
Send audio to ADAT1/2 and see whether a signal arrives at the ADA8200 by connecting speaker to output 1/2.

> On the Fireface settings side, should it be set to internal or Optical in?

Already told in post #4 :
Babyface seems to be or should be clock master.
Check / ensure in the RME driver settings that clock source is set to "internal".

> I would post an image but i don't see an option for that.
The usual thing: save image to a cloud (e.g dropbox) and post URL with an image tag.
Either add the tags manually or select the URL with the mouse and click to image icon of the forum editor.
See also: https://www.tonstudio-forum.de/blog/ind … rum-EN-DE/

Works as designed ;-)

You used the pitch function of the driver to reduce the sample rate by -0,417%, see manual chapter 8.2:
https://www.rme-audio.de/download/bface_pro_d.pdf
https://www.rme-audio.de/download/bface_pro_e.pdf

Set the ruler back to the center and you will have 48 kHz again ...

Don't worry be happy

There is a 1:1 relationship between output channels in the DAW and software playback channels.
The final routing happens then in TM FX where you decide per HW Output which SW playback channel(s)
you want to hear on this particular submix.

This picture shows how you can organize different audio streams on your PC.
I created this picture for another thread, but its also useful here.

Do you see ? You can split audio very nicely by sending audio to different outputs.
The good thing is, at that point its not being send to the real outputs of your recording interface.
Its only being send to "virtual outputs".

Next step in submix mode is to route the required audio to the HW outputs as needed by simply raising the faders of
- HW inputs (audio directly from the HW inputs with near zero latency)
- SW playback channels (audio from PC/ applications with the usual RTL (round trip latency) via USB/FW/etc..)

And this is a diagram which shows you the signal flow when working with external HW.
In Cubase its very easy to define external devices, so that you can use it like a VST.
There you only need to define the HW input and the HW output.
Latency is being calculated automatically.

Don't get confused, it's easier than you think.
Start slowly.
RME offers different videos to various topics: https://www.youtube.com/user/RMEAudio

Maybe this one is helpful from the title ..
https://www.youtube.com/watch?v=ApwZyRTTmc0

Here I offer a nice collection, but maybe not containing the last recent ones:
https://www.tonstudio-forum.de/blog/ind … al-Videos/

I made a primer for the 1st setup steps:
https://www.tonstudio-forum.de/blog/ind … rnal-equi/

And the manual is your friend ...