Digital Mixer... Yes a CD4052 will give you a dual 4 channel audio selector and an LM1036 (sampled from TI/National) will give you a DC operated Vol, Tone and Bal control IC. It's a plan I intend to implement. Is a copy of the sketch you have for the 5767 available?. I bought 2 of them yesterday, one to play with and one to use. The only other requirement you will have is some buffer amplifiers as the tone control IC wants to see 1V levels as I remember. NE5532's should work well there and I have a lot of them. I've attached data sheets for both IC's and the for the LM1036 the volume control can be used W/O the other stuff...
Bob
CD405X.pdf (193 KB)
LM1036.pdf (394 KB)