I have an Apogee Symphony I/O that I run in USB mode. Unfortunately, using USB, the Symphony can not lock to external digital sources. You need Thunderbridge for that.
That being said, I still hooked up the SPDIF between the Kemper and the Symphony, and I was able to record and reamp using the SPDIF connections.
I was surprised this worked as I understand the Kemper can't lock to an external digital signal, and thus both clocks would be running independently. I called Apogee, and I was told, they are probably running so close that you aren't noticing, but you are still probably getting subtle aliasing and drift. I'm wondering if it is this, or did the Kemper OS get updated to be able to lock to an external source?