prototype or new kemper rack or fan made ?????

It is a (bad) photoshoped picture. Look closer and you'll see many mistakes. So it can't be a prototype.

I guess it is a "wish" from a user. Maybe from the time the rack version wasn't available yet (was the black head uncovered bevore or together with the rack? I don't remember that...)

I don't think we'll see new hardware from kemper within the next 5 years or more. Of course there would be some things in hardware that could be improved, but for me, continious improving firmware comes first.

Exactly, this is a fan-made photoshop that was around before Kemper showed the actual rack version of the KPA. I remember seeing it in an old thread in this or another forum about the Kemper hardware

It doesn't even reflect the signal flow from left to right.

Not ergonomically laid out either. Thankfully the team put a whole lot more effort into the design than whoever concocted that picture did.