There is a simple "trick" you can use to reduce the power supply noise on low-power (preamp) audio circuits.
Put a diode & resistor (~100 ohms) in-series in-between the regulated supply and the op-amp. Then, a filter capacitor (~100uF) in parallel across the op-amp power supply inputs to ground. (You will loose about 1/2 to 1V across the diode and resistor... This is not an issue with +/-15V supplies, but it could be a problem with a 5V supply...)
The diode very-effectively blocks any negative-going noise (as long as the capacitor holds-up the voltage), and the resistor & capacitor form a low-pass filter to reduce any positive-going noise.
The resistor limits current into the op-amp, so you can't use this trick with a headphone or speaker amplifier, but the diodes can still be used.