A user from AndroidForums, balu_radu, found a way to change audio gain settings.

BE CARREFULL ! DANGEROUS SETTINGS ! YOU CAN BREAK YOU PHONE !

- Download http://www.drakaz.com/FILES/TMP/servicemodeapp.zip and http://www.drakaz.com/FILES/TMP/AudioFilter.txt

Extract servicemodeapp.zip in /data/app_s :

adb remount
adb push serviceModeApp.odex /system/framework/
adb push serviceModeApp.apk /system/framework/

- Push original AudioFilter.txt (prevent conflit with modified AudioFilter.txt and servicemodeapp tests) :

adb remount
adb push AudioFilter.txt /etc/

Then, reboot, and let’s try some settings !

headset music volume hack :

dial *#*#197328640#*#*, [8] audio -> [2] headset -> [2] rx value -> [5] rx codec for midi -> [1] rx codec gain, enter 5FFF for 4db, 7FFF for 6db, FFFF for 12db, 2014 for default

headset in call volume hack :

dial *#*#197328640#*#*, [8] audio -> [2] headset -> [2]rx value -> [1] rx codec/volume, enter 5FFF for 4db, 7FFF for 6db, FFFF for 12db, 4000 for default

speaker music volume hack :

dial *#*#197328640#*#*, [8] audio -> [3] speaker -> [2] rx value -> [5] rx codec for midi -> [1] rx codec gain, enter 5FFF for 4db, 7FFF for 6db, FFFF for 12db, 47d0 for default

speaker in call volume hack :

dial *#*#197328640#*#*, [8] audio -> [3] speaker -> [2]rx value -> [1] rx codec/volume, enter 5FFF for 4db, 7FFF for 6db, FFFF for 12db, 5a67 for default

Restore default settings :

[8] audio -> [5] Rebuild all

I repeat, BE CARREFUL with servicemodapp.

Discuss about the best settings on the forum : http://www.drakaz.com/forum/viewtopic.php?pid=593

Original thread by balu_radu : http://androidforums.com/samsung-i7500/77088-found-headphones-volume-hack-i7500-samsung-galaxy.html