For me hiss was a big problem with the kemper but it was maybe cause i received a malfunction hardware (i send it back and i'm in a tie to think about the Kemper)
I did only one profile cause of my direct output problem, it's a little fender frontman, in clean position.
You can hear the hiss is really bigger with the profile than reference amp (first amp reference then profile, a- b a -b a-b etc...)
This sample is all through the kemper (direct output in amp, sm57) but with my direct output problem if there is more hiss cause of that, it must be the same in amp and the profile right ?
On my monitors the hiss seems to be 1,5 or 2x bigger in the profile than the amp.
http://soundcloud.com/mugiwara-4/test-profiling-a-b-frontman