Hi, Is it possible to use the DDM4000 to control traktor on my laptop without using an external sound card? I connected the DDM4000 to my laptop with a midi to usb cable and connected my speakers to the out B channel. When I open traktor I can control two channels with the mixer but I can't use any other features, my headphones don't work, and the sound comes out of my laptop in stead of out of my speakers. Can anyone help me? Thanks!