i am running cab sim off, I think the issue is cut and fullness of the tone, basically need to increase volume so I can hear myself.
I think the problem is more in the 600w solid state power amp, it sounds thin and weak in the mix, I tried Marshall el35 monoblock 2x50w all tube power amp, feeding monitor out, that thing actually sounded much much better and I could hear myself..
The problem with digital is, that it's missing some frequencies that a real tube amp would have, not sure if you can get that fat tone you need to get in the mix with digital at rehearsal...
Not if you're running correctly made Merged or Direct Amp profiles. Then all the tone and interaction of any tubes in the power section are captured and the clean solid state power amp of the Kemper will reproduce them without adding colour of its own. If you're using regular DI profiles or Studio profiles, then you might be right.