
All programs work with this setup because all programs are able to play to the default sound output device.

Now playing audio to the default audio device will play to both of your audio devices at the same time, no matter whether sound from programs or system sounds. I failed with the Audio Repeater KS (kernel streaming) version because of 100 % usage of one CPU core but I succeeded with the Audio Repeater MME (MultiMedia Extensions) version (no visible CPU usage). Use the Audio Repeater program included in Virtual Audio Cable to play Line 1 to the other output.Mirror the Line 1 recording device (the recording end of the Virtual Audio Cable) to one of your outputs: This is done in the Properties window of Line 1 on the Recording page of Sound settings: Check Listen to this device and select one of the outputs in the list box.This is done in the context menu of Line 1 on the Playback page of Sound settings.

