There are two audio equalizer options for users of PulseAudio. The “hasn’t been updated since 2010” pulseaudio-equalizer package, and the “oh, surprise it’s not really ready yet” qpaeq. On Fedora, at least, both are pretty broken and representative of the “looks good but doesn’t work” philosophy too common for the Linux desktop nowadays (the very philosophy that caused me to leave Windows to begin with, and to never really give Mac a try).
I recently installed the pulseaudio-equalizer package on Fedora 21, thinking it might be nice to have the ability to, well, do equalization of my audio inputs. The rpm installed just fine, but my audio output stopped working after I fired it up and applied a preset.
With qpaeq my experience was similar. The yum package manager installed the pulseaudio-qpaeq package alright, along with its dependencies. But when I ran it from a console (the package doesn’t include a .desktop file for a menu item), I got an error
There was an error connecting to pulseaudio, please make sure you have the pulseaudio dbus module loaded, exiting...
Oh, so helpful.
Failing to find anything about qpaeq in the Fedora doc and fora, I searched around a bit and came across this thread regarding using it on Ubuntu 14.04 LTS. Turns out what I needed to do first was load a couple of PulseAudio modules via the command-line (as a regular user, not as root or sudo root):
pactl load-module module-equalizer-sink pactl load-module module-dbus-protocol
After that qpaeq would run, although the presets selector was blank and didn’t allow you to select anything.
Basically more negative advertising for Freedesktop.org, where half done software gets thrown against the wall to see if it sticks. Honestly, sometimes I wonder if their budget isn’t substantially underwritten by a Steve Ballmer trust — because what they’re doing is making Linux as dysfunctional as Windows.
Note: In the process of exploring this I confirmed that doing a “pulseaudio -k” as root is still not a good idea (it may require you to reboot). Doing it as your logged in user isn’t very wise either, because it will probably result in your having to log out and back in again.