Virtual Audio Cable installs software audio input and output interfaces on your PC that can be used to take the sound coming from one app and turn it into microphone input for another. The software is odd in that there is no main window where you can pair input and output apps together; it is instead done right from those apps' settings.
Deep Windows integration: Each "cable" that Virtual Audio Cable installs is actually a pair of software input and output devices. This setup is completely independent of your actual microphone and loudspeakers, not relying on them in any way -- so much so that you can use this software even on a machine that has no hardware audio input and output devices.
Advanced cable settings: There is a control panel where you can customize the sound that's traveling through the virtual cables, including specifying the number of worker threads, the audio format range, the number of cables, and controlling the stream buffer. We recommend trying the default settings and using the control panel only if necessary; also, make sure that your PC exceeds Windows' minimum hardware requirements or your audio may stutter.
A steep learning curve: Since the software operates in an unusual way from the vast majority of apps, it is vital that a quality tutorial is made available on first launch. Unfortunately, that's not the case; you're left with a documentation that has its most informative section, Usage Examples, buried near the end of it.
Not all apps are compatible: Due to its mode of operation, which requires that you search for audio input/output options in the settings pane of third-party apps, this software is incompatible with any third-party apps that don't allow custom audio input/output sources to be set.
Dangerous software upgrades: Be sure to uninstall your current version of the software if you intend to install an updated one. Not doing so will mess up your virtual cables.
Although a powerful piece of software, Virtual Audio Cable lacks intuitiveness. Even its documentation is not structured optimally, as it is there to provide a college course in audio input/output technologies rather than get you up and running in as little time as possible.
Editors' note: This is a review of the trial version of Virtual Audio Cable 4.14.