Shoutcast as the source, streaming to dual player instances (Winamp or whatever player), each tied to a different sound card. Since it's streaming from the local system, it should have either no delay, or *equal* delay between each player (provided you set the streaming playback buffers for each player to be the same!). Note that you should be able to setup Shoutcast to play not just MP3s from e.g. another Winamp instance, but also the loopback or line in or whatever else, thus it should be able to stream any audio on your system...
- Oshyan