Ok here is a little guide on how to mirror your audio on two different devices (soundcard and Rift)
The trick is to put your sound card (in my case Realtek) as the default device, if you have the Rift set at the default device and try to mirror it to the soundcard it doesn't work, only the soundcard mirrored to the Rift. Don't ask me why...
So here you go
First open up your sound options and set your soundcard as the default device:
In my case it's the Realtek High Definition Audio
Then go to the Recording tab and right-click...Select Show Disabled Device. This will bring up the Stereo Mixer. Right-Click on it and enable it.
Once it is enable, go into the Properties of the stereo Mixer
In the Properties, go to the Listen tab and then check the box "Listen to this device" .
Under the "Playback through this device, select Headphones (Rift Audio) from the drop down menu
Finally on the Advanced tab uncheck Allow applications to take exclusive control of this device
And that's it you are all set, you will now hear the sound from your speakers and your Rift!
You can adjust the listening levels in the Levels tab of the Stereo Mix properties, but raising the volume of your PC will still raise the volume of your Rift, you can just create a volume offset between the 2 devices.
It does create a tiny lag between the two device but the sound is still in sync with the image so don't worry about it
I am a spacesim/flightsim/racesim enthusiast first :-) I7 firstname.lastname@example.org, 16gb RAM/ Asus 1080 Strix Former DK2 Owner/Gear VR owner/CV1