Do I understand you correctly : the kemper works fine with the Konig converters?
Background: I am planning to buy the RME BABYFACE pro fs and I like to use THE SPDIF out of the Kemper. But the Digital Input of the Babyface is different.
So, please let me know, which cable and adaptor / converter I need to have.
Sorry for the super late response but I'll answer for posterity. Since Babyface Pro (and FS version afaik) support S/PDIF connection over TosLink optical connection you need to convert TosLink to Coaxial and vice versa in order to connect it with the Kemper in both directions. You'll want this two way connection if you want to do re-amping but also to avoid issues that might happen if you don't fully close the cycle.
The white, digital coaxial cable with RCA connectors should go from the Kemper's S/PDIF out connector into converter's coaxial input connector. The black, optical cable with standard TosLink connectiors should than go from the connector's optical output to Babyface's optical input connector. The same is true the other way around where you have a different convertor which is converting optical to coaxial connection and go into Kemper's S/PDIF input connector.
It's important to note that Kemper's S/PDIF supports digital coaxial cable with RCA connectors (not Mini TOSLINK / 3.5mm connectors one might assume). One example might be https://www.amazon.com/C2G-29115-Velocity-Digital-Meters/dp/B0002J2B8I or https://www.sweetwater.com/store/detail/GoldRCA03--mogami-gold-rca-rca-cable-3-foot. The one I use is a custom made one from the local store.
The other important part if you are going to do re-amping is to configure Babyface's optical output to use S/PDIF (the default is ADAT) in order to send the DI signal to Kemper: