Create a virtual audio output device

In Linux, you can use the following command to create a virtual audio output device. With this virtual device, you can turn the volume in. This will not make any sound physically, and you can stream the desktop sound to other apps like streaming/recording apps.

Without the virtual device, you will have to turn the sound on physically to stream it to another app. One another trick is to plugin an earphone and turn the volume in.

sudo modprobe snd_aloop

Source: https://unix.stackexchange.com/a/174395/147676