djm master outs

hi  . I have DJM 900 . and i am useing it a  a new venus   i know they have a built in amp and  speakers .   i  also have some active speakers , question is . i may want to use both sets of speakers  so  the mackie's will have to  use the XLR. so  which other main out will i use ? the 6.3 trs  booth  or the rca  masterout. ?  thanks in advance  guys