@rgloenberg I think you got that wrong.
If you use the Powerhead into a Cabinet, just leave the DI-Profiles as they are.
The poweramp of the Kemper doesn't shape or influence the sound in a way a valve poweramp would (Can't tell if it influences the sound at all).
DI-Profiles have captured Pre- and poweramp of a certain amp, and the Kemper Powerhead will drive a cabinet and sound exactly like or pretty close to the original amp.
So you just load a DI-Profile, let the Powerhead drive the cabinet, and it should sound like the original Amp plugged into that cabinet.
If you use the non-powerhead Kemper and run it into external poweramps (for example the FX-Return of your Mesa Rectifier), this poweramp will shape the sound in its own way.
And as this sound has gone through 2 Poweramps (1 already profiled, 1 "real"), it may sound strange, or muddy or sth..
In this case, it would be smart to turn off the "Cab" section of your Kemper, which reduces the poweramp-influence of the originally profiled Amp by a big amount.
What you have left then is basically a Preamp-Profile, that you can now run into an external poweramp and into a cabinet. And it should sound great then!
With that second method, the sound will differ from the originally profiled Amp, as you basically run the preamp stage of the original amp into a different poweramp stage.
So if you want to get to the original amp sounds as close as possible (without buying the amp ), you need a Kemper Powerhead or a really linear poweramp.
Tl;dr: Turning off the "Cab" section of a DI-Profile reduces the amount of poweramp-influence of the originally profiled amp.
You might wanna try this if u use an external poweramp, but not with a Powerhead (Otherwise it may sound horrible)