First of all, the quality of music being played is bad, i think somebody said the driver is still in experimental stage. So, we skip that quality issue for now.
About the volume, if I plug a earphone directly into the Pi, the maximum volume is pretty low, i used the "alsamixer" command to adjust the volume to the max, and whatever software i used to play music, has maxed, the adjustment on the earphone also maxed, comparing plugging the earphone to a PC and to the PI, it gives very significant difference(max out all), playing the same mp3 file. The only different is I am playing it from debian(Pi) and from Win7(PC). Need to know is it supposed to be like that ? or the driver improvement they are doing will somehow increase the volume too ?