Ok, wow - there's some bad advice here. Music is about ears not eyes. There are no 'peaks and valleys' there is no 'look at the spectrum analyzer and fill the gaps' - there is only "if it sounds good - it is good." If you send me a song or mixtape or whatever to listen to, I don't get the spectrum analyzer out and think "well, it's all pretty even - good song!". I listen to it and if it sounds good - it is good. You should get to know the sound of your speakers in your room and mix with your ears. To get to know your speakers listen mixes you've done in other places (the car, other stereos, ipod, laptop) and compare what you're hearing there to what you heard when mixing.