In this video I'm using an OPUS-QUAD to control rekordbox 'Track Separation' also known as Stems. The OPUS-QUAD, just like the XDJ all-in-ones double as a midi controller when connected to your computer & most, if not all controls are midi assignable, including the hot cues. So you can access the MIDI section & remap it. just note that the LEDs on the hot cues do not light up when you use them for stems. Consider a MIDI controller if you don't want to remap your controller.
Sidenote: the DDJ-800, 1000 & XP2 utilise a PAD mode (not MIDI mode) function which allows you to assign Track Separation/Stems. Once I get my hands on one I'll make a video on that.
