Where's the midrange ?

Quote from old crow

I'm a newbe and using a pair of JBL LSR4326P monitors. Sound is pretty good with some guitars, esp. L.P.'s but can be quite fizzy and lacking mids for the most part. Doesn't sound close to my Carr Mercury.
Headphones are better but still not even close to the sound I get from the Merc.

First question is since you are playing through monitors are you sure you have cabs turned on for whatever output you are using? No cab on would likley mean fizzy and no mids through a monitor. Also, I find for me, I have to turn the presence and treble down a lot to get the sound I like out of my monitors and headphones. Don't be afraid to play with that EQ. The KPA has powerful EQ that you can use extreme settings with and it will still sound good.

Hmmmm. I had a Carr Mercury for a while that I swapped a Celestion Blue into. It was a beautiful and pure sounding amp that had a beautiful rounded fender-like tone. You may not be able to exactly get that sound without a good profile of the amp but you should be able to get a round or even chimey fender sound from lots of profiles.

Have you tried a general system reset (hold system button on startup) just to make sure all settings are default and have you tried some of the better profiles out there with cabs such as Tills'?

I think what you are experiencing is the miced up sound phenomenon.
The profiles are of a miced up amp, and sound just as a miced up amp does. The mic itself plays a huge part in the sound, very much emphasising highs and lows.
You will probably get a lot closer to the (amp in the room) sound of your Carr if you switch cabs off and use a power amp/cab.
Does the carr have an fx loop?
If so you can try this out by plugging the monitor out of the KPA into the fx return of the carr, switch the KPA cab sims off and see if this is the kind of sound you are looking for.

Quote from old crow

So I'm thinking , when profiling an amp it's best to do it "hot" then roll it off when using it thru the Kemper.

That has been my conclusion--I set the gain on the amp higher than I want for the rig and then back it off in the Kemper.

Well, mic placement and mic type is huge. I notice a lot of people like to use more "full range" styles of mics, and I never think that does a better job... in fact, the good ol' Shure SM57 is still my favorite mic for guitar cabs mainly because it does such a good job of capturing mids. Make sure you experiment with mic placement. Don't go by where you think it should go. Place it where you get the best mid range response. Also, when profiling don't be afraid to crank your mids a bit to over emphasize them if you don't feel the profile is getting the mid range you want. Again, mic and cab are crucial... even the room can make a difference. Remember, what sounds good on it's own is often terrible in a mix. Rig presets often capture what a good guitar sounds like alone but need to be properly EQed to sit nicely in a mix.

Last, but not least, is don't be afraid to use the Kemper's EQ post cab. I'm pretty sure I've never left a miced guitar cab unEQed in all my born days.. either live or in the studio. Before you go boosting, make sure you roll off your lows and then increase the volume of the overall signal. Usually I find this does the trick.

Quote from old crow

Now that's using the old penis. I need to take more of a mixing approach playing thru this Kemper w studio monitors. I'll give that a try.

OK, it is kind of old, but it still works really well... well pretty well. I didn't use it to answer that question though or the answer would have been really different.