apt-cache search equalizer | grep pulsepulseaudio-equalizer - Equalizer sink module for PulseAudio sound server
it is not a parametric but If you resize the window horizontally, you'll notice that more bands show up so using it, you have very high control
Imprecise question. No clarification.https://www.youtube.com/watch?v=2_DrW067JmI
Thanks includemeout. mmrkaic couldn't be more obvious what it is here for with its 100% fitting to the pattern reaction so i left it uncommented.
You're right. Leave him at it.