Basic Bending Diagram from “Add Volume, Jack” (Weekend Projects)
For me, one of the pleasant side-effects to circuit bending with mono-speaker toys is the ability to leave the original speaker embedded in the device, while still having the option to amplify the device when you’re ready to rock out on stage or for an art installation. This means I can always hear the toy when I want to, without needing a full PA or powered speaker setup.