I have a dell Latitude D610 and I want to use a mixing software to begin DJing.... I need to play the music out loud on my PC speakers and also use channel 2 on the mixing program for my headphones. I bought a USB to audio cable so i can plug both my speakers and headphones into. It doesnt work anyway, the music comes out of only one, the speakes (left and right to mix) and same as headphones. Anyone know why? Is it the sound card????