EQ's are made to compensate for a non-linear response.
those who use EQ's for tone control are showing an example of disrespect towards the producer's wishes when the original was mastered live during recording.
usually i find myself lowering the bass because the producer did something to compensate for his/her lacking system.
you are supposed to use an EQ to make your speakers speak flat on the frequency curve, and then LEAVE IT ALONE.
(not like there are an exceptionally high amount of mastered audio works out there anyways)
one album i sincerely recommend for a before & after comparison of speakers/headphones that have not seen equalizer calibration - opposed to - speakers/headphones that have seen equalizer calibration:
artist: daft punk
you will learn that the album has much more class than the choices of sound that was used, but also the volume that these sounds were implemented.
kinda like.. did the artist pick black or white? WHAT SHADE OF BLACK? WHAT SHADE OF WHITE?
shading makes a difference