Designing single supply audio - what best way to get a clean reference ground?

[azone]

I haven't done much with a single supply, the job I'm working on has some restrictions.

The circuit is actually powered from an AC supply, not batteries, so the voltage regulation is not perfect. The main positive supply is an LM317. The output is 10V, the voltage regulation is probably about 4mV or so. This is fine to power all op amps and other IC's, transistors.

I'm not sure if it's feasible to split this 10V supply to derive a 5V bias voltage to use as the ac ground. I'm not sure how clean this virtual ground needs to be. The circuit is all pre-amp stuff - with signals in the range of 20mV to 1V.

If my virtual ground has 4mV of ripple in it isn't that going to effect my circuit by causing a lot of distortion?

or is it not really that important/audible?

Would you get a better reference by using a 5V reference diode like an LM336Z-5.0 (since it's dereived from ground and not the shaky positive supply)?

[Conrad Hoffman]

Which ever way you go, you'll bypass your mid-voltage to ground with a good size cap, so the ripple and noise should be microvolts, not millivolts. Naturally the reference will be better, but you still need to bypass it to kill noise.