Same thing is happening to me. Everything was working fine a couple of weeks ago, I've been traveling and I haven't played since then.
Today I turned the Kemper on and I was shocked with the sound, scepecially all the clean sounds were horrendous.
I have tried with all the outputs and only with the headphones, plugged in my home and in a different place and I'm getting the same results. I did a Factory Reset and the same thing is happening with the Factory Rigs. I don't know what to do.
Did you find any solution?
Thanks!