Headphones not showing

SO i Bought  ddj 400 and in my audio settings my headphones are not showing.

First I treid to connect some external boxes to the ddj 400 with the white and red cable, but no sound was coming out. So I connected the boxes to the pc and set it so that the sound is put out throu the pc. THats working but still not really what I want. 

My biggest problem is, that on the "headphones output" setting there is only "outputchannel 1 and 2" which are my left and right boxes. I can not choose any other settings for the headphone outputs. I looked for a driver but the website tells me that there is no driver for the ddj400 and when clicking on the driver button in the settings I can't find any ddj-400 driver.

Would love to get some help