you can take the audio from the pot, which is called "pro sound mod". if you like you can bypass the potentiometer.

the ground can be shared on the two RCA's. look at this pic:

please note that this pic stands for the so-called "internal prosound mod".

Look at the pin labeling on the potentiometer, it will give you an idea.

edit:

here it is

i've never done this mod, but this scheme in theory should be right.

I want to put RCA jacks on my DMG, but need some help with it. Can i just solder the RCA wires to the same motherboard points as the headphone jack and just leave it like that, or will I have to do something more "extreme"? I still want to be able to use the normal headphone jack please.

Thanks