Hi,
It's because an amp can be modeled with a DI Box (without a virtual or real speaker cab)--this is a "direct profile".
You can read more about Studio, Merged and Direct profiles here. I'd suggest reading the manual too.
As mentioned, the KPA just separates the elements out in case you want to change them.
IR's are less important IMO for the KPA and I never use external IR's. I tend to just use the profile itself and sometimes swap the cabs around.
I would go farther than profiling... Cause no one told about the most important ; your goal and what you would be able to do with the profile you've made (Or NOT).
Like every modeler, Kemper offers the possibilty to send the "All Chain simulation" to FOH and only amp sim via monitors output. The way to obtain this is to split your chain somewhere (don't know why, but between the amp and the cab 
) ....When you profile a combo, The profiler guesses where the Amp is and where the Cab+mic is too.
You don't have to profile another time if you want to have the configuration i talked about above.
This bring you the possibility to go on RIG Exchange, choose a rig you like and change the cab section section for another one or go to an actual speaker....
As harmonik said, plus if profiling with a cabinet and mic, the Kemper profiling process estimates the split between these to allow you to swap the cab/mic of one rig with the amp of another.
This.
One aspect that can be confusing is how the Profiler deals with cabinets. There are three fundamental types of Profiles:
- Studio: Amp and Cab Profiled together
- Direct: Amp Profiled without a cab
- Merged: Combines a Direct Profile with the cab from a Studio Profile (basically create a Direct and a Studio Profile of the same amp. Store the cab with the Direct profile to create what's called a Merged Profile. Now you have Studio and Merged versions.
Personally speaking - I completely ignore which is which. I'll mix and match amps and cabs with zero regard for whether the Profile is Studio, Direct or Merged. I'm going for a sound and don't much care how I get there.
The argument against this is often "doing that isn't authentic". The (overly) sarcastic side of me says "Yeah? .....and??"
/rant on
These aren't the real amps to begin with. I've never been in the same room with most of these and played even fewer of them. So...why bother being precious about a sound I've never actually experienced?"
I have a sound in my head I want to achieve. If that's the exact sound of a Marshall Bluesbreaker (or whatever), that's a complete accident.
/rant off
Sorry.....either too much or too little coffee this morning.
There are two main schools for digital amps:
- Get an exact sound from a certain amp.
- Have access to a lot of amps you could never afford.
For me there is a 3rd option: Take amp head A and stick it on speaker cab B. When I bought my first Pod, I was like a kid in a music store swapping everything everywhere.
OPTIONS
There are close to 20k profiles on Rig Exchange. A lot of them are made by amateurs with bad mics, mic positioning, etc. The Kemper lets you take these profiles and split the Amp out. Then you can add an IR from a purchase or another profile that was done professionally.
Conversely, you can get a great IR/Cab from a bad profile. I use some cabs for high gain amps that I pulled from low gain profiles for example.
For me there is a 3rd option: Take amp head A and stick it on speaker cab B. When I bought my first Pod, I was like a kid in a music store swapping everything everywhere.
This describes me fairly well, also. Boiled down, it reminds me of a line in the movie 48 Hours. Eddie Murphy as Reggie Hammond is shaking down a bartender, dropping glasses on the floor "Let's see....what we....can F@3k with next...."
It's only overwritten if you save the Rig. Saving it as a new Rig with a different name will give you both.
So when I take a rig and import it in and it shows the name of the Amp and Cab, this is the amp/cab that was profiled correct? the cabinet is automatically entered in along with the amp? if I turn off the cabinet block then the profiled cabinet will be disabled? if I choose another IR in the cabinet block then I'm overwriting the profiled cabinet for another cabinet? or am I just combining that profiled cabinet with another IR?
It shows the name that someone typed in, so assuming they typed it in correctly, yes. The KPA doesn't automatically know what amp or cab its profiling - the name is only a label.
The KPA works out in the sound profile what part is cab and what part is amp. For a studio profile, this is an estimation, its not 100%.
When you swap cabs, you are swapping the estimation of 1 studio profile for another. In this context, IR's are the same as Cab's.
Just to confuse you, it is possible to have a much closer representation of this split by using a direct profile and an external IR....and I haven't even mentioned imprints through the kone...
The lesson here? Don't worry about it! You have the flexibility to change amps and Cabs in any combo you like. You can import your fav IR's if you want.
This is why IR's are not so important in the KPA and are just another sonic rabbit hole - because you can swap the cabs around from any other profile.
Hope that makes sense.
Kemper's vocabulary is destabilizing when you come from modelers ; cab/amp you catch what it is but ;
Rigs, Performances, Morph, profiles ?! 
Even a speaker is called a Kone 
