Virtual Audio Cable Full - free downloadVirtual Audio Cable software allows you to transfer audio (wave) streams between applications and/or devices.
It creates a set of virtual audio devices named "Virtual Cables", each of them consists of a pair of the waveform input/output devices. Any application can send audio stream to an output side of a cable, and any other application can receive this stream from an input side. All transfers are made digitally, providing NO sound quality loss.
VAC behavior is similar to "What You Hear" (or "What U Hear", "Stereo Mix") feature of Sound Blaster Live! and Audigy cards. But it is only similar, not equivalent. If you simply need a function like "Stereo Mix" under Vista/Win7, there could be better to try to enable it in your audio adapter.