Ubuntu or PulseAudio actually really needs a good system wide equalizer. A project which initially begun as a simple script (actually it still is a script) now has become a fully working system wide PulseAudio equalizer. In the recent version, thanks to psyke83 the script comes with:

• a GUI
• .deb installer and presets (based on VLC's built-in equalizer) - so it's really easy to install and use by anyone.
• 15 frequency bands you can adjust to your liking;
• preamp will boost your equalized volume (as a multiplier value from 1x to 4x);
• you can save your own presets

Once you install it, if there is no menu entry under Applications > Sound & Video, run this command to get a desktop shortcut:

cp /usr/share/applications/pulseaudio-equalizer.desktop ~/Desktop/

Then double click it and select "Mark as Trusted".

You can download the script and get support @ ubuntuforums.org | Direct download link*


*I suggest downloading the script from the ubuntuforums.org since new versions may be released. Only use the direct download link if you don't want to make an ubuntuforums.org account.