Maybe "unnatural" and "clipping" are not good terms as such, but there is still an audible "snap" every time one hits the strings for the first time:
... Listen to this track (from 0:34):https://soundcloud.com/shainsth/two-test-reamps-mesa-randall
...
Nakedzen: it is so weird that I can't avoid the spikes and you can't produce them, no matter how hard you try 
We could spend endless hours trying to narrow this down to something by trial and error. But at least in my case, I cannot easily investigate the effect of pick (and playing style/touch for that matter), string gauge/brand/material, guitar (and its construction/electronics), pickups, cables, audio interface, Kemper settings, firmware versions, Kemper hardware etc ... just because I don't have any extra stuff or extra time!
So unless we collect a lot of data from many users in a systematic way, I'm afraid such a reverse engineering approach might not lead to a solid conclusion.
My workaround so far is to adjust "pick", "compressor" and/or rig volume to prevent the peaks from clipping (yes, they are there but not clipping anymore).
IMO, it would be best to have the mothership comment on this in a serious manner...
I received my powerrack about three months ago, so I have not done too many firmware upgrades yet. Maybe the spiking behaviour started at some point (since nobody has complained about it before).
Would it be safe to downgrade the firmware far back in time to see if the old ones behave this way as well?
Mr. Kemper,
We feel that it is odd for the profiler output to go red if one just very lightly touches the strings with the pick edge. This event is associated with audible clipping and a spike in the beginning of the waveform, hence all the pictures in this thread.
The same effect seems to take place often when one starts to play after a period of silence (especially with high-gain profiles and also depending on the playing style a bit, I guess).
It is also unclear (to me at least) to what extent real amps behave this way.
Any clarification would be greatly appreciated. 
Some great examples there, I appreciate your help! One thing that crossed my mind is that at least in my case many (if not all) of the profiles that exhibit spiking have a boost pedal as part of the profile (i.e., _not_ added as a Kemper stomp). Coincidence?
No word from DonPetersen yet.
Nakedzen: what guitar and especially pickups did you use? Can you post a waveform example?
More examples would be great, since there might not be actual clipping if the output volume is down, but the unnatural transients might still be visible.
I imported "KM-THRASH" from the firmware directly, didn't touch anything. Oh, and the cab section was not (accidentally) locked as far as I can tell if that is what you mean.
I just noticed that the soft shaper in position X didn't remove the spikes with any reasonable settings, but "compressor" set to 1.5 or so did tame the ugly transients with the "Bombed!" and "KM-THRASH" profiles (for instance) to a level where they didn't stab my ears anymore. They are still visible in the waveform, but there is no clipping. At least this is one obvious way to deal with it.
Think hard HELL-G, there has to be a difference and that difference might solve this issue for me too 
viabcroce: I don't have a chance to try with different guitars and the picking/microphone position did not hugely change the situation based on quick testing.
Trazan: Are you referring to the fact that all of the peaks point upward or what? If so, then what might be causing it?
Here is a close-up of the very last spike of the wav in the first post fwiw:
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Viabcroce: the compressor is at "0" (neutral?) default position. Actually I have never touched the compressor setting in any of the profiles I have onboard.
Nakedzen: my gut feeling is that the spiking doesn't happen with all profiles. Did you test with the profile "KM-THRASH"? Some of my waveforms are indeed spikeless when recorded through spdif, although I can't recall the specific rigs right now. All I know is that spiking happens also with Lasse Lammert's "Bombed!" profile, which is annoying 
Djuhntt: this is a good tip, will try it thanks!
Thanks a lot HELL-G and others! At least I know my Kemper is most probably healthy
Unfortunately I don't have access to a tube amp at the moment, so I can't tell if this is the expected behaviour. Anyone willing to comment on this? Does this happen in real life too?
About the amp parameters: increasing “clarity" makes the spikes smaller, whereas "tube shape”, "tube bias”, "power sagging” had no effect as far as I can tell.
The parameter “definition” had a minor effect, but as one might expect, the parameter “pick” affects the peak behaviour the most. Decreasing “pick” from 0 to -1.5 reduces the spikes so that the output no longer goes red. However, for real playing I’d like to be able to set it to +1.5 instead, so I am hoping this is not the only solution...
Could someone else quickly check this behaviour? Take the profile “KM-THRASH” and see if there is a huge difference in the output level between sudden pick attacks (the spikes) and continuous playing.
With the stack or the amplifier off, there is no problem. The waveform is much narrower of course but the spikes are gone.
It just unfortunate that this happens with almost all good sounding high-gain profiles. 
The question is: is this the way real tube amps behave or is this an artefact?
I get similar results with the main outputs as well... The waveform is pretty much identical, including the peaks.
I don't know if this is a problem or a feature, but often when I play the first note (let's say after a small break in the song or something), the output led goes red during the pick attack.
Here is brief test. I am using a factory rig by Keith Merrow, "KM-THRASH". No stomps or effects. Clean sense -6.3, output through spdif to Roland Quad Capture. Noise gate 5.0. Firmware public beta 2.2.0.8917B. Guitar is Schecter Blackjack w/ Seymour Duncan Full Shred.
The problem (to me at least) is that when lightly touching the strings with the side of the pick (the first eight peaks in the wav), the output goes easily red and I hear a sound that is a bit unnatural and reminds me of actually clipping the output. This doesn't happen if I use similar pick attack while strumming chords (as in 0:03-0:11 in the mp3 clip). In 0:14 one can hear the problem again very clearly, I hope.
I am pretty sure that the output with headphones behaves ok, so maybe this is spdif related?
https://dl.dropboxusercontent.…mper-pick-attack-test.mp3
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Oh yes! The drums are especially nice, what did you use for them?
I still haven't explored all the sounds from the rig pack (I am in love with the "Bombed!" profile, can't get past it, fingers hurt ...), and now this!
I like this a lot! Which profile did you use?
