I have been doing a bit of research on these units do they really bring something to your music at that price
I also use Traktor pro along with Native Instruments S2 controller and Ableton & Controllers all fed through my oldish Native Instruments Audio Kontrol soundcard which sounds fantastic with real punch and clarity and my Audio Kontrol doubles as my usb soundcard for all sound duties from my macbook to my speakers and sub
Are you using traktor and dj’ing straight of your laptop’s headphone jack without using a controller?, and if so then i guess you’ll be using your laptop’s inbuilt soundcard which will not be up to the task, check out the Native Instruments Audio 2 soundcard which is very decent for little money and connect one output to your amp using an rca to stereo phono splitter (usual red/white plugs) and the other output for headphone cueing, or you could buy a controller with inbuilt soundcard such as the Numark Omni pro and connect it up to your amp unless you are running active speakers (with built in amps) in which case connect your speakers straight up to the soundcard or omni control/mixer.