Newer version of Ubuntu's will have Pulseaudio installed. If it is not installed, then go to terminal and type
sudo apt-get update
sudo apt-get install pulseaudio
To get equalizer, first download pulseaudio equalizer from here.
Download
Now go to Applications->Sound and Video->PulseAudio Equalizer.
Here you can see the snapshot of pulseaudio equalizer :)
You can select the mode of output and save presets :)
Enjoy with better quality sound from now on :)
Thank you for reading this article :)