Sounds like digital distortion ..... If you mean that "crackling" noise while you´re playing lower notes ? 
Is it supposed to be a "clean" sound / rig ?
-12 dB pad activated on main output ? Any LEDs blinking red somewhere , KPA out , interface , DAW ?
Have you tried with TS cables ? Line in setting in interface ?
Or do you mean that hiss and soft G-tone at the end ??
Cheers !
Just throwing this out there:
Are the XLR outs on the Kemper at LINE-LEVEL? Then connecting them to the interfaces XLR MIC-LEVEL preamps? This will be putting a much higher voltage signal into the preamp than it is designed for. I normally see people saying they need XLR -> TRS cables to go into the LINE LEVEL balanced inputs on their audio interface.
I am a noob so I just use TS ->TS all LINE-LEVEL signals.
Use TS <-> TS and see what happens.
Display MoreNo I mean the hiss in the background..
I made some new tests now!
One of the files are with a telecable (mono). And I have made 2 tracks to duplicate L and R.
The other file is with Mono XLR mono, and duplicated.
Do you hear the difference? Is it normal everything you hear on both of the tracks?
Much better 
Both tracks sounds "normal" .... only a very very weak "buzz" at the end ....
Maybe from a computer screen or other electric gizmo in your room
Try another one, and then at the end turn down volume from the guitar and
hear if it gets dead quiet ....
If so, your pickups pick up something from something 
Cheers !
Just throwing this out there:
Are the XLR outs on the Kemper at LINE-LEVEL? Then connecting them to the interfaces XLR MIC-LEVEL preamps? This will be putting a much higher voltage signal into the preamp than it is designed for. I normally see people saying they need XLR -> TRS cables to go into the LINE LEVEL balanced inputs on their audio interface.
I am a noob so I just use TS ->TS all LINE-LEVEL signals.
Yes! When I use XLR Cables, I set the audio interface to Mic level instead of Line!
shall I change any settings on the Kemper when I use xlr you mean?
Now I think it sounds ”okay” with the xlr cables! But I think that the ”hiss” in the background is still a bit annoying ???
It is a different noise when I compare the cables to each other
Yes! When I use XLR Cables, I set the audio interface to Mic level instead of Line!
I think the Kemper only puts out a LINE LEVEL signal. I do not use it that way so I do not know for sure. I hoped some of the pros on here would fix you up. I was just trying to quickly get you on the right path 
Yes! When I use XLR Cables, I set the audio interface to Mic level instead of Line!
shall I change any settings on the Kemper when I use xlr you mean?Now I think it sounds ”okay” with the xlr cables! But I think that the ”hiss” in the background is still a bit annoying ???
It is a different noise when I compare the cables to each other
The Kemper puts out a Line Level signal. If you are using XLR cables you need to make sure your interface can accept Line Level signals NOT Mic Level on the XLR input.
