As you already know, OBS is the leading software for DJ streaming. That being said, I would like to inform you about the following issue with your software on Windows 10:
Traktor sends, via USB, both the master audio and the cue audio to OBS, without the possiblity to separate the two sound sources.
Of course, you already recommended using an external audio interface, but that is costly.
Rekordbox and Serato have solved this issue by creating a virtual master out to send only this signal.
Please fix this.