When a speaker is put into a room with walls, floor and a ceiling, reflected sounds from these boundaries can cancel or reinforce one another further altering the frequency response. ...
At higher frequencies, hundreds of small peaks and dips can be measured in the frequency response. ... Resist the urge to equalize these frequencies.
At low frequencies (below about 300 Hz), the picture is different. ...
With equalizers, less is more. Limit your use of the equalizer to lowering the largest bass peaks that typically occur below approximately 300 Hz, and you will likely have good results.