RCA audio mixer.
I used Flitzing to reset the pcb in the future
You could do this circuit just by cutting out some RCA cables and connecting the resistors directly in the line. But if you want a little cleaner, you can make the pcb and print a box, in that circuit not the need for power supply.
List: Female RCA Port https://goo.gl/Jmogoy
Resistor 10k https://goo.gl/aJtvh9
Thanks, it's all personal!
Source = http: //www.cheeptech.com/atarivox.html