the best way to use traktor is to have a soundcard with 2 or more stereo outputs feeding a normal dj mixer. This way you can monitor as normal. if you want to use to computer mixer, then again you would need a soundcard with two stereo outs or have to split the audio into two mono channels to enable one to act as the master and use the other for monitoring...not ideal. A duo called 'digital motion' were using turntables and traktor at the holodeck (our night) recently and I was impressed with the results. They were using the external mixer method but also had a controller a bit like a phatboy controlling the filter etc. I'm going to look into using this myself.......