oh yes, that is something i dont like too. I will take a look at how it works (if it is controlled by rockbox) when I'm back from holidays (2 weeks of no head-fi ).
I guess there is a relay after the output capacitors. This lets the output capacitors charge over the internal resistor not over your headphones when power is switched on (when no music is playing, output be ~4.5V not 0V, thats why we need output caps). If we don't wait long enough, it is not entirely charged and you hear a pop.
schematlic looks maybe something like this:
If the relay is controlled by kernel, maybe we can't do anything. Maybe also a hardware mod is possible, if the relay has a NC contact, this contact could be used to charge the cap in the time between power on and sound-initialization.
I will take a look at this but cant promise to be able to do something.
Edited by cholero - 7/3/14 at 10:34am