Yes
You seem to have the same need as https://launchpad.net/ubuntu/+spec/equalizer-for-sound-out .
There is a solution that, as requested, is Ubuntu-compatible, not tied to any specific hardware. It has 15 bands, from 50Hz to 20kHz.
Solution is described in System-Wide PulseAudio Equalizer Updated For Ubuntu 14.04 and 14.10:
This tool provides a 15 band equalizer interface for the LADSPA sound
processing functionality of PulseAudio. It supports enabling or
disabling equalized audio on-the-fly, comes with some built-in presets
(based on VLC's built-in equalizer), supports saving your own custom
presets for later use, can be used for the current session only or
permanently, etc.
To enable the system-wide equalizer for the current session, check the
"EQ Enabled" box and click "Apply Settings". If you enable "Keep
Settings", PulseAudio remains permanently equalized (and therefore,
you won't need to run the PulseAudio Equalizer interface each time you
login).
This document (in French) https://doc.ubuntu-fr.org/pulseaudio-equalizer
summarizes to:
sudo add-apt-repository ppa:nilarimogard/webupd8
sudo apt-get update
sudo apt-get install pulseaudio-equalizer
or
sudo add-apt-repository ppa:alex-wv/pulseaudio-equalizer-ppa
sudo apt-get update
sudo apt-get install pulseaudio-equalizer
Then run pulseaudio-equalizer-gtk
, check "EQ Enabled", adjust settings, check "Keep Settings". It will apply to all applications.
I've been using it on Ubuntu 14.04, 14.10 15.04, 15.10, 16.04.
Only, left and right channels are not independently controllable as you requested. Is that last point important? Since program is open-source, that could probably be adjusted for.