pulse audio equalizer
To start the pulseaudio equalizer run:
qpaeq
If this gives you the error
There was an error connecting to pulseaudio,
please make sure you have the pulseaudio dbus module loaded, exiting...
then load these two modules using pactl:
pactl load-module module-equalizer-sink
pactl load-module module-dbus-protocol
and, to make these changes permanent, edit ~/.config/pulse/default.pa (create it if necessary) and add these lines:
load-module module-equalizer-sink
load-module module-dbus-protocol