Good lord they've got a lot of amp profiles that come with that thing. Holy Crap!
Worth going to their site just to look that over.
I was semi-wrong/right.
You can profile with a mic in front of a cab but you can also profile
just the pre-amp by sending a line level from the pre-amp out (effects loop send ) back to the Kemper instead.
It doesn't take a speaker level signal.
But I don't see any reason you couldn't use a speaker box/att of some kind that gives you the speaker out at line-level.
They don't mention that but if it'll take line level outta the loop then line level is line level; so there should be a way to get your amps' power section also if you wished.
You'd just have to get a line level signal off the speaker-out to do it.
I may e-mail them and ask about that.