In GroundControl CASTER you can combine multiple audio devices and audio from applications into one virtual audio device.
All CASTER tracks are routed by default to “CASTER stream Mix” audio device. So all you have to do is to open CASTER app and add your application tracks, add your Microphone tracks and add your Inout tracks (any audio device you want).
All the tracks will be routed to “CASTER Stream Mix” virtual driver, as well as to your headphones outputs. you can control each track audio level independently and create a different mic levels for your stream and for your headphones.
On top of all that, you can use “Direct To” from each track in CASTER app. this will create a virtual audio device in your system and route only this specific track audio into it. for example you can add application like FireFox, enable the “Direct to..” option, this will create a “CASTER FireFox” audio device in your system that will grab all the Firefox audio into it.