I don't think this is a PSU, but I'm willing to give you a hand, purely so I can be called a Guru.
Start with have a look at www.blackwidowaudio.com
They're a pretty good resource for such circuits.
I managed to find this one which does pretty much what you want by the look of things.
As you only want the pre amp stage you won't need IC3 & IC4 or ony of there supporting junk.
This will only solve the difference in output levels, to get around the .5v offset you should be able to use a ground isolator avalible from car audio stores or alternatively apply a voltage offset to IC2.
Well that's a starter for 10, as they say.
Rob (MP3CAR GURU)