I've been experiencing this forever and only recently realized after speaking to another KPA owner that it's not normal, or at least not to their experience.
If I'm jamming in "tuner" mode, as I often do, there are extremely audible/annoying/messy audible subharmonic notes being produced in response to my playing. I know that sounds crazy, but listen to this:
It only happens on some of the 'stabs' in the above example, but this definitely sounds wrong and I'm worried that those audible tones are occurring underneath my playing but are only detectable when I stop abruptly. This isn't a huge issue, but it makes it impossible for me to track guitars while in "tuner" mode. Since you're tuning between every take in the studio, it would be really handy to just leave it on tuner mode the whole time, but this makes me weary of that.
Anyone else experiencing this? I'm on the latest firmware but this has been happening for as long as I can remember.