Is there some application or module that will give me control over EQ, sound for the system? (And I don’t mean just mp3’s played in Amarok, but anything from flash played in a browser, to HTML5 videos to mpgs, mp3’s etc)
AFAIK pulseaudio-equalizer-gtk can do this.
Over many versions the eqalizer/mixer controls are directly related to whatever sound sub-components and Desktop you have installed.
So, for example pulseaudio equalizer is likely appropriate for 11.4, not anything before and not guaranteed for anything later.
And as 6tr6tr forgot to reveal what level of openSUSE he uses, the answer is just a wild guess.
The disease of not telling what openSUSE/Desktop one runs seems to be rather abundant today