Reply to Denon DN MC6000, Traktor Scratch Pro, Audio 4 DJ and Two SL1200s - Help Needed

I've just replaced my Pioneer DJM600 with a Denon DN MC6000, hoping to use my Technics to control 2 decks in Tracktor Scratch Pro 2 (I originally had Scratch Duo and upgraded, so only have an Audio 4 DJ soundcard) and use the DN MC6000 to control the other two decks.

It seems impossible to set this up correctly as I can get all four decks working in Traktor using the DN MC6000 on it's own or just two decks (the Technics) using the Audio 4 DJ.

Has anyone had any success with this, as I'm drawing a complete blank and hoping someone will be able to help work this out.

Cheers