Offizieller Kommentar
The DJM-250MK2 is not intended to control the internal software mixer as it's capable of receiving discrete audio outputs from the software to each channel of the mixer, and then mixing the audio in hardware.
The hardware on all Pioneer DJMs is always "audio first," so even if you were to configure it to manipulate the software mixer via MIDI, any audio passing through that channel would be affected by the position of the knobs / faders.
Set it for external mixer mode and you'll find it's a better experience.
