Since today the Kemper is making noise, never had that before. I already sent a mail to Kemper about that, but may be someone got an idea for help.
Here´s an audio file (dropbox link) of that noise. All cables are fine, noise is also there with no cable in input:
https://www.dropbox.com/s/cavvbl5t6ae8…sch_03.m4a?dl=0
Any ideas?