connecting djm900nexus ,rmx500 to my lenovoG505s laptop running win7 usb from mixer or rmx?

im connecting djm900nexus , rmx500 2x cdj850ks to my lenovoG505s laptop running win7 should i connect usb from mixer or rmx to laptop i have been using set up as follows mixer to rmx to ua25 soundcard then to laptop and amp,surley i dont need to go through Edirol ua-25 aswell seems to me 1 extra device i shorly dont need given the soundcards built in to my gear already, or do i ??