Loopback for Mac
Publisher's Description
From Rogue Amoeba Software:
Loopback gives you incredible control over how audio is routed between applications and devices on your Mac. With just a few clicks, you can easily pass audio directly from one application to another. Loopback's virtual audio devices make it trivial to arrange complex audio setups that were difficult or even impossible before. It's like having a high-end studio mixing board right inside your computer, with no physical wires required.