[hackerdork]

andrew that sounds like you have stereo mix or what-you-hear selected for the default recording source.

I do a simular setup with external mixer, coming into laptop with the DSP LINE-IN, and I have select the LINE-IN as the recording source inside windows , click lock on the push to talk and I have my mix and other devices from the mixer coming into the stream.

if you have the soundcard out from laptop 1 or 2 into the mixer of course the window sounds would come in as well, we dont really want that so the broadcast computers should have their sound scheme setup for no-sound, so im twitter and other application dont make a noise into the mixer.

so ...

LAPTOP traktor.. -> Mixer channel #. mains out to laptop 2 (winamp with shoutcast).

should work but again the laptop running traktor need to have the system sounds off.

hope that helps