I did not know where to post this, so I put it in the KPA related discussion....
Here are my humble thoughts on the Kemper and maybe on digital sound engineering (as I would call everything from POD to AXEFX to Kemper):
The Kemper Profiler is a very cleverly designed piece of engineering. My understanding of the way it works (gathered from what I have read about it) is that it measures the even and odd harmonics produced by an slightly or heavily overdriven tube amp (or ss amp if you will). By means of elaborate test signals it analyzes the distortion behaviour of the amp profiled. This data is then somehow used to "emulate" the amps behaviour, so that you can tweak the harmonic content to some extent.
The Kemper always takes a pic of the whole signal chain: guitar, tube amp, speaker, mic, mic preamp.
So in fact I think it analyzes not only the harmonic distortion content of the amp, but also the frequency "profile" of the whole chain.
This it does very very good.
The Kemper is a tool like your guitar, fx, amp and cabinet. A very handy and mighty tool, but it is not IMHO more. Same for the AXEFX (I have only heard the AXEFX never played one) or any other modeler. Tools to be used to express yourself.
I can dial in a extremely nice sound and wail away at home, I can plug into the Kemper in the studio and get a fantastic sound very fast, I might be able to use it on stage (have not tested that) with a nice PA. But still it is a tool, nothing more.
I think there might be some misinterpretations concerning what the Kemper can do:
For example that you take a cabinet from one profile, or to be precise take a frequency analysis of a cabinet and a mic and a mic preamp and some room reflections, and apply this cabinet to another tube amp profile. But you always have to remember that almost every tube amp interacts with the speakers and cabinet. With the speaker by global negative feedback and the output transformer, with the cabinet that will react to the speaker soundwaves and even reflect that back to the amp.
I tested it myself by profiling two very different amps (Marshall style OD to Dumble style OD) using the exact same cabinet, exact same mic and mic position, exact same room, the cabinet nor the mic were moved. Yet when I "extract" the cabinet from one profile and apply it to the other it does sound very different? Why? Because both amps react differently to the speaker or vice versa.
I used to own an Eleven Rack. And in direct comparison, the Kemper is much more organic sounding, a huge leap ahead, better feel, better sound.
Yet real amps sound still different. In the real world, the amp and cabinet interact with the room, they interact with you and your preception of sound. A 100W Marshall Plexi blasting through a 4x12 at you will be different from a Kemper profile of the same amp blasting away at you through some linear high power monitor. Since the 4 speakers in a 4x12 react differently to the signal from the amp, there are numerous phase cancellations and a lot of stuff going on I can not even put in words. Then there is the psychology of having a real Marshall blasting at you.
So again it all boils down to the fact, that the Kemper is a tool, just like a real Marshall. The Kemper can do a whole lot more for you, FX, silent wailing, extreme control over sound etc. Which one is better?
You can not say which one is better, because they are different. You simply cannot use a 100W Marshall on 11 anymore (yeah, eat your heart out Spinal) during rehearsals. And a Marshall on 3 does not sound like a Marshall on the edge. So you can use a reactive load on the Marshall to bring the volume down, yet that will also sound different.
Then take an AXEFX. As said I never have played one myself, only heard it via YT. Nice sounds to be had, tweakers delight. For me that would not be the right tool, because I want to spend more time playing than tweaking (and I know of Scotts video in which he brilliantly showd how to set up a preset very fast). I personally need a different approach, I feel at home with the Kemper controls, the simplicity. Is the Kemper better than the AXEFX?
That is the wrong question. Like asking a carpenter if brand x hammer is better than the hammer from brand y. The carpenter will pick one out of a multitude of excellent tools, that fits his personality and needs the best.
We are all constantly trying to get a better sound, easier rig etc. That`s our human nature, this makes the world go round. What I find distracting is the waste of time spent on forum "wars" where it is discussed if the AXEFX or Kemper is the best thing invented since sliced bread.
To end this, I will give an analogy:
Hammond Tonewheel organs have been around and used since 1937. If you have ever sat behind the mighty B3, driving two Leslie 122 you know what an unearthly instrument this is (or listen to some early Santana with Gregg Rolie). Since this instrument weighs about 150kg and the Leslie approx. 60kg, people tried to "emulate" the sound. They tried hard and in the beginning (Korg) they came up with a tool that was nice, but very far away from the real deal. Nowadays you have plugins and everything, but still nothing sounds and FEELS like a real Hammond. But! Times have changed the musician/artist has to use something lighter, easier to carry around and this is where all the great digital engineering devices come in today and makes people play!
So for me the Kemper is a fantastic tool. Kudos to the inventors. Same goes to the AXEFX. Pick your tools.
Dote