Depending on your specific hardware/drive combination you may not need a virtual audio cable at all. If your soundcard driver supports it you can use "stereo mix" in the sound control panel.
Right click on the speaker icon in the system tray, select "Recording Devices". Make sure you are in "Recording Devices", and not one of the other possible selections, like "Playback Devices".
If "Stereo Mix" is in the selection area set that as "Default".
Now whatever audio is being sent to the speakers, no matter the source, will be routed to record.
If "Stereo Mix" is not a possible selection you may be out of luck with this approach, but maybe not. Typically at least "Microphone" and "Line In" are listed. Right click in the clear are below whatever is the last thing listed. Make sure that both "Show Disabled Devices" and "Show Disconnected Devices" are checked. If no "Stereo Mix" or "Wave Mix" is on the list then you cannot use this approach. If either are on the list enable them, and select as "Default".
T!