QUIET RIOT
First, try running
alsamixer
from the command line. If there is still some headroom on any of the sliders, bump them to 100%. Sometimes there are weird interactions between the different volume sliders, and making them all 100% could increase you output volume.
IT AIN'T ENOUGH
For even more volume, we can head to the commandline.
pacmd list-sinks
will list all possible sinks for volume increases on your system. To bump my volume to approximately 200% (100% is 65536), I used:
pacmd set-sink-volume alsa_output.pci-0000_00_1b.0.analog-stereo 125000
This will increase noise to some extent (looking into some good ways to filter it), but at least those quiet sounds can now be heard!
http://askubuntu.com/questions/219739/adjust-max-possible-volume-in-pulseaudio
