Hi,
I recommend you to use Standalone version of StereoTool, EdCast and Virtual Audio Cable.
Edcast is free and Virtual Audio Cable(s) unfortunately not.
If you stream mp3 or AAC or both, in EdCast you can easily change lame or aac codec, which is not case in shoutcast dsp encoder.
Latest EdCast:
http://users.tpg.com.au/radiorio/
Virtual Audio Cable:
http://software.muzychenko.net/eng/vac.htm
Setup:
Winamp output VAC1 > ST input VAC1 > ST Output VAC2 > EdCast Input VAC2
If you need to hear music while playing try Multiple output plugin, where you'll select your soundcard (for listen) and VAC1 (for sending to StereoTool)