Audio design

So, my focus for design at this point is focusing on mediation/augmentation of two senses - sight and hearing. I'm waiting for the opportunity to buy more head-mounted displays to experiment with, so in the meantime a large part of my work is going to focus on audio. I've been considering the merits of different designs, and there are different merits to each.

The audio setup needs to combine the audio outputs of carried radios, the wearable computer itself, and worn microphones. My goal for it is to have a central mixer that can combine the signals, adjust their volume relative to each other, allow them to be adjusted to the left or right channel or any combination thereof, and feed signals from one device into another. For now it seems prudent to build one that's controlled manually, but I'd eventually like there to be a simple method of computer control.