There’s a really cool equalizer for Pulse Audio which can be installed by adding a repository. Its a system wide equalizer hence no matter what media player you use, you will be able to utilise this setting.
The image below is a screenshot of the same:
How to install:
Open the Terminal (Accessories > Terminal) and type in the following:
sudo add-apt-repository ppa:psyke83/ppa
Next type the following in the Terminal:
sudo apt-get update
Finally, type the following (in the Terminal of course)
sudo apt-get install pulseaudio-equalizer
Thats it. You can access the Pulse Audio Equalizer from the Sounds & Video menu.
Update: The creator of this Equalizer has added a new .deb file for both 32 and 64 bit versions of Ubuntu 10.10, simply click on the following link and install: Download Link