One must not forget that although a sound level device will allow the user to setup the speakers equally all on sides, their ears may not be hearing at equal levels.
This is often true of those older in age that may have any extensive amount of hearing damage from years of concert going or even someone who's had a blown ear drum or ear infection decreasing the perception of sound on one side.
Sometimes using just your ears will actually help to setup your HT the way your individual ears like to hear it.
