Hello!
You cannot have them connected without syncing via BNC.
BUT, it's not that the UR824 does not play well with the D8s. It's because BNC connections, need a 75 Ohm termination resistor to work properly.
So, you need to get 2 of these:
https://www.thomann.de/de/pro_snake_bnc … ImRlIn0%3D
and hook them to each of the D8s.
Then, you need to go:
UR824 BNC Out -> (BNC cable 1) -> D8(1) Angle T connector(hooked to BNC In) -> (BNC cable 2) -> D8(2) Angle T connector(hooked to BNC In)
and at the other end of the connector, you need to put this: https://www.thomann.de/de/pro_snake_res … ImRlIn0%3D
All this will take care of the BNC Clocking issues, with the UR824 as Clock Master.
After that there are two options:
1. D8(1) ADAT Out -> UR824 ADAT In(1) and then UR824 ADAT Out(1) -> DigiFace ADAT In(1)
D8(2) ADAT Out -> UR824 ADAT In(2) and then UR824 ADAT Out(2) -> DigiFace ADAT In(2)
This way, you set the DigiFace as slave(word clock set to "Optical 1"), but you only have the Headphones Output for monitoring(unless you have a 3rd D/A converter)
2. D8(1) ADAT Out -> DigiFace ADAT In(1) and then DigiFace ADAT Out(1) -> UR824 ADAT In(1)
D8(2) ADAT Out -> DigiFace ADAT In(2) and then DIgiFace ADAT Out(2) -> UR824 ADAT In(2)
This way, you set the DigiFace as slave(word clock set to "Optical 1"), and you can use your monitors hooked to the UR824 Analog Outs.
In both situations you would need to keep the UR824 connected and use its mixer for routing, along with TotalMixFX to take care of the routing on the Digiface side of things.
Either way, you need to use the DigiFace ASIO driver, and just keep the UR824 connected for its mixer.
Bear in mind, though, that I don't know if there will be any driver conflicts(I don't think so, but you never know)
Hope this will work out for you!
RME Gear: Digiface USB, HDSP 9632