Turning Monitor Cab Off if you’re running a Kemper into a guitar cab is certainly the way to go.
If the Kemper is second hand it might have some unusual settings you’ll want to undo.
In Output Module, have a look at the Output Filter page, there’s a High Cut parameter which will muffle your sound if it’s weirdly low.
Also, check the EQ controls (bass / middle / treble / presence) in the Amp Module. The Main Outs and Monitor Outs in the Output module also have bass/middle/treble/presence controls. Any weird treble and presence cutting there?
If that doesn’t provide a solution, I wonder if what you’re hearing is just down to what a Creamback can sound like.
Earlier this year I bought a Marshall DSL1 head (these days I buy valve amps solely to create profiles of them!), I tried it out into what the shop happened to have, a Marshall 1x12 cab loaded with a Celestion Creamback, it sounded very muffled (admittedly the DSL1 has no presence control), whereas the DSL1 into an Orange PPC112 loaded with a Celestion Vintage 30 sounded brighter. I have cabs with various Celestions, and find the Creambacks to be relatively dark. Sometimes this works - my Plexis (100w, 50w, and JTM45) sound so super bright on the bright channel that a Creamback can be an interesting option because they’re darker.
If you have access to a regular valve amp you might find it useful to try your Creamback cab with that, just to confirm that what you’re hearing is just what that cab sounds like. So you might want to switch to a different cab.
But you can always compensate for a cab that’s too dark by using EQ. Either the EQ controls above, or by putting an EQ into one of the fx modules.
You might also try the Definition control on the Amp pages. That can brighten things up quite a bit on almost any profile.
Thanks, I did all those things, and the most helpful was a post-pre-amp Studio EQ entitled, "Cut through the mix," which added a lot of high-end back.
....but.....
I went through the same journey, eventually realising that guitar cabs MASSIVELY colour the sound, way more than I ever realised. The Kemper just showed this up because it has so many options and the ability to go direct.
This is important because if you play live, you probably want to take your cab for monitoring but want to run direct - the sound will be massively different, and it took me ages to realise my guitar cab was masking a poor base sound.
I started with a 4x12, went to an FRFR speaker and now use the Kabinet and could not be happier.
I would never go back to a guitar cab unless I had to....
