Hi Seviien;
Equalizer settings are dependent on a lot of things...
* The response curve of your speakers.
* The response curve of your listening environment (the room you are listening to the music in).
* Room response has a lot to do with curves... how dead or alive it is. A dead room will have a lot of high frequency drop off. Carpet, drapes, and heavy cloth-covered over-stuffed furniture can really kill a room (acoustically speaking). On the other hand a very live or overly bright room will have too much high frequency content as it reflects much of the sound wave from the hard surfaces.
There is no correct equalization curve. Yes there will be one for your equipment & listening environment but in order to get that perfect curve a spectrum analysis has to be done using pink noise, a calibrated microphone and a spectrum analyzer to provide correction factors (in Db or Octave correction settings) for your environment.
If you change speakers (or move your current speakers to a new location), buy new furniture, of redecorate you listening environment, the whole environment has to be tested again & the new octave settings applied to the equalizer.
You can buy all in one audio test equipment that is designed for the do-it-your-selfer at home. It will often look just like another piece of hi-fi gear except it comes with a calibrated microphone and is designed for just that one task. It will also have 1, 1/2, or 1/3 Octave correction sliders to make the corrections. Some of the more expensive units will actiually make the corrections automatically. Often they will also feature a real light show with moving Octave LED's moving up and down as the music plays. Many units have 10 or more rows flashing of LED's and can be pretty flashy. You can spend anywhere from a few hundred to well over $1,000.00 (or much more) for it.
Is it worth it, in same cases very much so as it will correct for all kinds of problems with the final reproduction curve. The A-B sound difference is often very striking.
Hope this helps (a little).