djm750 not playing sound while rekordbox is active

So, when I have rekordbox up and running, it is not playing my music or sound(from my browser or another music program) off channel one on my djm750. 

So my question is, does rekordbox override the soundcard even if my cdj 850s are set to channel 2 and 3 on rekordbox DJ?(output 3 & 4, 5 & 6)

My setup is as follows:

DJM 750

2x CDJ 850s