Looking back at post #20 of this string, you said the Kemper sounds fine through headphones or when directly connected to your monitors. If that's right and you're using the same rig you are recording then your problem can't be with your Kemper, your guitars or with your monitors.
Then maybe somehow in the settings on your interface or how you're connecting to it. Maybe try to rule out SPDIF as well by trying a recording with just the analog Kemper output. Set Kemper Main Output to Master Stereo (or Master mono). Check the Main Out -12db checkbox. Set all of the Main Output EQ's to zero. Verify that it sounds as you expect with headphones on the Kemper or direct to your monitors.
Connect the Main Out to your interface and make sure you're not clipping the input. Record it and if it's still got the problem you might need to try help from the interface vendor. If it works analog, then maybe it's something in your SPDIF settings