Managing 4 audio sources and switching between 2 outputs

[m.figman]

I have 4 audio sources that i would like to be able to mix and and possibly control their volumes. Then be able to switch between 2 outputs, speakers and headset.

The audio sources are all 3.5mm audio, the speakers are RCA or 3.5mm and the headset is USB or 3.5mm.

 

[Alabalcho]

Search for "stereo audio mixer", this is what you need. There are model with USB interface, ready for PC/Mac processing.

 

[americanaudiophile]

Here's a do it yourself solution
http/www.instructables.com/id/Altoids-Tin-18-Stereo-Mixer/
Build it with two outputs instead of one or add a switch to select which output will be active.
You won't be able to use USB headphones easily of cheaply.