Wow! And here I've been slogging through accomplishing the same thing by using a big clunking rotary switch, a relay shield, and a Kits R Us preamp kit (with the 4 linear pots replaced by an AD5206).
I don't know whether to scream or rejoice! In any event, I certainly owe you a beer or three.
Is there a DIP mount version of the TDA7313 that will support more than three multiplexed inputs?
Thanks!
I was thinking the same paths before, using digital pots in a regular audio circuit.
TDA7439 have 4 inputs and is SDIP30, problem is SDIP don't fit on a breadboard the pins are closer than on a DIP. I have also looked at TDA7719 that one have lots of inputs and nice features, that is TSSOP28, but you could use a breakout board. I have both circuits but have not tested them yet.
/K