For FM output it's not working correctly yet, but...
http://www.stereotool.com/download/dsp_ ... _BETA2.exe
This should work for the Winamp plugin.
The defaults are set to match the Winamp defaults, if your settings differ, click on "Configure audio and display", and change the timing at the bottom. It should match the Winamp buffer size (right click -> Options -> Preferences -> Plug-ins -> Output -> your output plugin -> Configure -> Buffering, and then the value filled in for "Buffer length".)
Of course you can also tweak it manually.
NOTE: This value is NOT yet stored when you close Stereo Tool. I'm working on a lot of changes (as you can see when you try this version), and I'll add the saving part for all of them simultaneously when everything is (almost) ready.