This is the front panel board for my modular mixer project. I wanted a simple, low-noise active audio mixer to bring together up to 4 stereo channels and provide master volume outputs for left and right, as well as stereo send to subwoofer, and line-level bus outputs (pre-master) for recording.
On it's own this board really doesn't do much - it's just a bunch of slider pots and the mixing resistors.
It has to be used in conjunction with the dual op-amp modules I designed for general purpose opamp circuits. These can be configured as line buffers for stereo inputs, summing amplifiers for the bus masters, and standalone for almost any other purpose such as tone controls. You can see the design for those here.