Question: I am constructing a signal generator using a kit. Upon soldering it together, I have encountered a problem. The board is marked with two potentiometer slots, identical except for the values named on the board: 50K for the amplitude control and 1K for the offset control. I have two potentiometers, nearly identical. One of them is completely unmarked. The other has B503 etched on the back. How can I tell which one is 50K and which is 1K?

Thanks.

Answer: 
It won't work as you wish - the ground in the circuit must be connected to the most negative supply rail i.e. the -5V rail. You might be able to couple your audio to the circuit thru a capacitor but it could be quite noisy. This could be overcome with an audio coupling transformer but, maybe just try running it from a single 5V rail (yes it will work at 5V or even 4V for some versions) then consider using a boost regulator to give you a clean (after extra filtering) 10V or 12V.
I've seen this amp operating with positive and negative rail supply

I've seen this amp operating with positive and negative rail supply
<https://www.youtube.com/watch?v=1zRamh9HMQc>

which should be no surprise really. Then you don't need the output capacitor.