Why My Kemper Sound is Bad and muffled?

Id try a factory reset first...
Global eq setting?

Yeah, reset may be a good idea, because these monitors should give you very good results.

Are you ssure re the monitors are good? Tweeters not blown etc?

What’s it like through headphones?

Welcome @NADIRICA here are a few ideas...

Check your cables. A great profile might sound "dull" at a low volume level, turn the volume up a bit. You could try turning pure cab off or adjusting the definition in the amp menu? Maybe use an EQ in the stomp section. Put new strings on your axes.

Maybe a setting is locked, like the High Shift on the cab. When something is locked, it will still the same for any Rig you load.

Is the Lock button lit up at all?

Very strange... and abnormal...

If I were you, Id pick my guitar and my Kemper and would go to see a musicien friend ( i got many) and plug it in his system...

I dont know if you can do that but this is what i suggest... try to isolate the problem, it can be your monitering system after all

But if the Kemper sounds bad everywhere its broken ... thats for sure ...then send it to repair

Here it sounds superb, on my set of speakers 1 and on my second set and it souds good on my headphones too..it sounds good everywhere

Goodluck

Go into the output menu, shift through the pages until you see "pure cab", and disable it by turning it all the way off - or uncheck the box, if there is one

Having pure cab on certainly doesn’t make anything seem “muffled” on my system.

can you upload a recording so we know what do you mean?

Strange that through headphones its also the same. As @hendrix1406 says it may be worth posting a recording.

Have you tried lots of profiles and are they all the same?

And youre not a troll ... right?

Just post a recording and noone (hopefully) will think you're a troll