A short checklist:
1. DJ-Mixer closed?
If your FLACAST-producer does not work in "Expert Mode", please click the corresponding button. Now right mouse click at the audio bar. Audio -> DJ Mixer -> Use DJ Mixer must not be selected, if you want to use another Player.
2. Now open the windows audio mixer (Start -> All Programs -> Accessories -> Entertainment -> Volume Control). Select at the recoding window 'Stereomix' (sometimes 'Sum' or 'Loopback, the name depends on audio driver). Open the corresponding slider to maximum position.
Special hint for Vista-User (how to find Steromix)
2.1. Right mouseclick at the speaker symbol at the taskbar (... or Control->Sound->Recording)
1.2. select 'Recording Devices'
2.3. Right mouseclick at Recording Device-window.
2.4. Select 'Show deactivated Devices' (now you should see stereomix)
3. Select at the playback window Wave and Microphone (if required). Again open the corresponding sliders to maximum position.
4. Now play your files with e.g. WinAMP (or any other player)
5. For right balancing, choose proper positions of the sliders described above.