Volume control

[Robert1144]

How can I add a volume control to this circuit?

 

[FilipSebik]

Use a stereo resistor like this:
http://www.goldpt.com/passive tester.jpg
and then the out pins (to amplifier) go to the capacitor C1 and C2 depending on left or right audio channel

 

[Tha fios agaibh]

I'd add in pots like this with wiper arow feeding Lin and Rin