Less than 10mV is not considered low noise.
Linear power supply is simple with the LM317\/337 and LM78\/79 series.
Parallel can be, but not directly parallel, each output with a Schottky diode, and then together.
Power frequency noise of switching power supply? The switching noise inside is much more than the power frequency noise, so solve the switching noise first.
The cheaper ultra low noise is the TL5209, but only positive.
If the protection of the pre-power supply chip is good, the ultra-low noise power supply chip can directly use the reference power supply to amplifier low noise transistor (MOS) tube to build a linear voltage regulator circuit, the number of positive and negative voltage current depends entirely on the transistor (MOS), the choice is much more, build a 10A.