What are your Clean Sense and Distortion Sense Settings?
Do you hear this hiss when you listen with headphones plugged directly into the KPA, if you are using an unedited Kemper Factory Rig?
Do you have treble boosted in the Output Menu EQ?
My clean sense is set to +4.0dB and my distortion at 0. It can be heard through headphones as well. All output menu EQ is set flat.