Do you have speakers connected to your PC but sometimes still want to listen to something but want to do so in private on your headphones? Do you have a PC connected to your TV and use a certain pair of speakers when doing PC things and then when it comes to using your PC to watch TV you want to use them speakers too? I have a very basic and easy solution.
Right click the sound button (as seen with the red x in the picture below) in the right hand bottom tray near the clock, note it may be hidden and need to click the arrow to view it.
Head across to the Recording tab, different computers show different things, because I currently don’t have anything attached it shows No audio devices are installed.
If you see the above right click the blank space and choose show disabled devices something along the following lines should show but we will only be using the Stereo Mix today.
Right click the Stereo Mix and enable it, then access the Properties section.
Once in the properties we need to focus on the listen to tab, first we need to tick the box Listen to this device, then underneath we need to select the device that currently isn’t working but we want to duplicate the main sound source through to. Note: Before this it may be best to check what device is set as your Default Sound and Communications devices on the Playback tab, it is recommended to set the default to one of the internal ports such as the green audio jacks especially when using a USB or HDMI device, always try to set these as the secondary.
Once this is all done you should be able to hear from both upon the Apply button, at this time I recommend setting your first Default device in Playback tab at your normal listening volume then once again going back into the Stereo Mix and changing the level up and down to suit the volume of the second device. Now it is good to remember that if you change the default devices volume the secondary/Stereo Mix device will change the same percentage eg down will go down on both devices and up is up for both.
Hopefully this helps to fix up any issues with dual sound output.