equal is a real-time adjustable equalizer plugin for ALSA. It can be
adjusted using an ALSA compatible mixer like alsamixergui or alsamixer.

Alsaequal uses the Eq CAPS LADSPA Plugin as it's default equalizer
but you can change it to use almost any LADSPA plugin like mbeq from
the swh-plugin package. Though alsaequal is primarily intended to be
used as an equalizer you should be able to use it to control any
LADSPA plugin. It's similar in functionality to the LADSPA plugin
provided with ALSA but allows for real-time controls as opposed to
static controls defined in the asoundrc file. 

See the included asoundrc.example in the docs directory for ways of
setting up alsa. The mixer is started with: 'alsamixer -D equal'