Arduino turning a knob left and right with Digital PWM

Hey all i am trying to find a way in order to turn an car amp's bass level knob left and right using an arduino's Digital PWM pin. I am thinking that a stepper motor would be the correct motor to use in order to do this or no?

Also, would there be a better fitting motor to do what i am looking to do without much needed modifications to the bass level knob in order to attach it to the motor to turn it?

The bass knob looks like this:


Any insight would be great!

Do you have to physically turn the knob with some form of rotary means, or can you remove the knob/pot and replicate the signal from the wiper pin?

I can remove the knob im sure.

You can buy motorised pots, they are a bit pricey and not that common.
A digital pot ic is a chip with a virtual pot inside, you send the ic commands and it moves its virtual wiper, this would be and indeed is a typical way of doing what you need.
Some d to a chips can do the same thing.
Using common parts you could use a rc servo and a bracket to hold it.

Have a look here and see if this will do what you need:
**broken link removed**