Comment # 4 on bug 1172412 from Takashi Iwai

Well, my question was to compare the actual loudness you hear from both
USB-audio and onboard sounds.  For example, try to set "Speaker Playback
Volume" to the raw value 10 (of 31) on Kingston, and compare the loudness of
the output from onboard audio.  Increase / decrease the onboard audio, and find
the same loudness as Kingston, then read the dB value shown on the onboard
audio.  That's the value to be used for Kingston device, too.

For checking the onboard audio dB value, the best is to like below:
- Assume you test from the line out.  The corresponding output volume is "Front
Playback volume", and set this to 100% (0dB):
  % amixer -c1 cset name="Front Playback Volume" 64,64

- Change Master volume via amixer, e.g. raw value 30:
  % amixer -c1 cset name="Master Playback Volume" 30,30

  Then compare the loudness.  Increase or decrease the value and find out the
same loudness as Kingston.

  The dB level on your onboard audio is mapped between -64 and 0dB, i.e.
  the dB level can be calculated as -(64 - rawval) dB
  So, e.g. the raw value 30 is -34dB.

Check the procedure above for different values of Kingston volume.  You can try
three or four different points, then we can estimate the dB mapping.