I have not made A/B tests with and without additional RC filter, however I believe PS filtering and cleaning never can be too much.
What exactly we hear in phones or speakers? We hear PS, slightly modulated with audio signal, think about it this way.
Even if PS dirt is not listenable as background noise, it can reduce music clarity and transparency.
To be honest, I did not made special calculations, just take large enough low ESR caps and 1 ohm was what lying in my part box and what I usually see in others low voltage CRC PS filters.
Schematic I posted is mostly for part numbers, related with my PCB, they are different from schematic in the page 1 in this thread. Part values is just what I use in my build, anyone can recalculate and use something slightly different.
10 ohm resistor in output is from original schematic (page 1 in this thread), I believe it is for protecting FET from short circuiting wen plugging phone jack on working amp.
If you believe, you can always plug and unplug phones with amp off, newer with amp on, you can short this 10 ohm resistor, probably gain in sound quality.
Edited by Zigis - 6/11/12 at 4:01pm