settings.xml changes the orginal equalizer.
even, you can do that with acoustics... editing acoustics to have big bass using headphone or headset is better than changing the orginal equalizer.
if you change the orginal equalizer you may have problem with the voice using loud speakers.
but acoustics can do that just when you use headset.
i may edit my acoustics to have mega bass at normal mode using headset or handsfree! ;)