I usually set the EQ straight up (unity) for the EQ section on my channel on the mixing board. However, I have already tuned the eq on my monitor channel to give me a flat response (using the auto-eq of a dbx driverack ).
What you are experiencing is probably colored sound from the mixer itself. Certain mixers are known for altering, or coloring, the sound a certain. For expample, some may give you a a slight mid boost or a slight low frequency roll-off. I think it has to dowith the quality of the preamps in the mixing board.
I'm not sure how complex your setup is, but I would advise you to get a buddy to help you tune your channel so that it sounds good to your ears.
p_music