Boost up the volume of your Nokia phone
It works with built-in Nokia Music Player.
The trick is...
Music Player->Option->Audio Settings->Equalizer->Option->New Preset->(Rename following presets below)->Set following the points in screenshot
Setting the equalizer it will make your speaker/headset sound loud. Here's The picture for the settings.
BASS+TREBLE
Just set your equalizer following my screenshot.
I prefer using this setting because it sounds clear and loud.
BASS BOOSTER
Edit: works with symbian 60 3rd edition phones. Will not work with s60v1 n v2.
Edit: Works with s40v3, the equalizer looks different but it works. Tested on Nokia 5200, Nokia 5300, and Nokia 6288.
ENJOY!!!