So...I haven't done the SPDIF thing with my Kemper as of yet. My interface has only the digital in. I haven't really looked much into reamping but I gather you need the digital out as well to back to the kemper if doing reamping, correct?
I will have a go at some point soon with the spdif in to my interface. I have to get one of those spdif to toslink convertors, unfortunately.
No0. Re-amping doesn't have to be done digitally, you can use an analogue connection for the return, and for the send as well if you like. SPDIF is just more ideal as it bypasses any AD/DA conversion and generally maintains quality better.