• code ALSA equalizer
    libasound2-plugin-equal - equalizer plugin for ALSA
    
    $ vim ~/.asoundrc
    ctl.equal {
    	type equal;
    }
    
    pcm.plugequal {
    	type equal;
    	# Modify the line below if you don't
    	# want to use sound card 0.
    	slave.pcm "plug:dmix";
    }
    
    # pcm.equal {
    	# Or if you want the equalizer to be your
    	# default soundcard uncomment the following
    	# line and comment the above line.
    pcm.!default {
    	type plug;
    	slave.pcm plugequal;
    }
    
    # alsa force-reload
    
    $ alsamixer -D equal
    
    $ vim ~/.bashrc
    alias alsaequal='alsamixer -D equal'