Virtual Audio Cable is a Windows WDM multimedia driver that allows a user to transfer audio streams from one application to another. Any application is able to send an audio stream to the output side of a "virtual cable" while a corresponding application can receive this stream from the input side. Since all transfers are made digitally there is absolutely no loss in sound quality. VAC is the audio equivalent of a MIDI loopback device such as MultiMid or Hubi.[1] The latest package, VAC 4, includes a 32-Bit and 64-Bit Windows Vista compatible version along with the previous Windows 2000/XP/2003.