guizmobro Hello Sir ! I've got the EXACT same sound from my kemper this morning.. How did you manage to get rid of it ? 
(if you did...)
I've tried 4 differents guitars (single coil, humbucker, passive and active pick up)
3 cables
Switched from the main input to the alternative one
Changed the power cable
and tested it without my audio interface ( headphone directly plugged to the kemper)
Is a power conditioner the solution ?