Give it a try. Take the potentiometer out of the DS carefully. It most likely will have three terminals. Connect your audio source to the right most terminal, connect the audio input to the mint tin amp to the wiper (the center terminal) and ground to the the left most terminal.
This is a fairly generic statement, assuming the pot in a DS looks like the kind in other toys. Basically you have a resistor with a sliding center tap. So you can use an ohm meter to determine which terminal is which. If the volume goes down when your expecting up, reverse the wires from left to right, leave the center tap the way it is.