So I tried to setup my cdj-400's with traktor. I want to use them as midi controllers for traktor sending audio out to an external mixer (djm-400). All seemed to go well, with making a new aggregate device driver and all. But in output routing I only have the option to choose Left or Right. So it ends up sending the track from deck A and deck B to both channels on my external mixer. I'm using macOS 10.13.6. Any ideas on how to fix this??