Maybe I am just looking for a "better than real" thing, but I have a small suspicion thet Kemper is a bit more noisy than a real amp. I don't remember, but I think back in the day when I was gigging with real amps I didn't have hum at such low gain tones. Maybe I am wrong of course.
actually it has less noise than its analog (profiled) counterpart.
did you try slowly rotating 90 degrees left and right? (you and your guitar that is, not the PROFILER) usually there is a position where there is no noise from external sources.
The PROFILER is an amplifier, not a noise generator
My guess is that computer hardware, a cell phone etc. is creating the noise you pick up.
If this were an issue of the PROFILER it would have been reported multiple times in the last eight years.