BAD: Brand New out of the box MK3. All keyboard keys were producing sound on Komplete Kontrol app except for the keys between C#2 and G#2 refused to play (a total of 8 keys). I noticed onboard firmware was 1.7.6 and Native Instruments had an updated Firmware version. So I downloaded the update and launched it.
WORSE: The updater launched on the computer and just as expected, the keyboard displayed 'firmare updating'. Then suddenly, the Updater gives a "An error occurred while updating your KONTROL S KM3" message. The keyboard now goes straight to an on screen "Looks like something went wrong" upon powering on and further attempts to update show that the onboard firmware is now 0.0.1.
$840+ dollars, had it for 2 hrs.
Sucks but likely returning this product.