hm. I have some really nice Altec Lansing earbuds that sound amazing with the default EQ using both the Music player and Pandora. Bass response is incredible, very well defined and even. Not too boomy, and all that jazz.
I also have a set of $5 'specials' that sound like crap. But they have a mic built in, so they go in the car.
Anywho, long story short, while I do like to adjust EQ on my music, I find that the default is surprisingly satisfactory. Perhaps the earphones you have don't have good bass response.
(typed while listening to some pretty intense Yes on my droid and loving every note of that Ric Bass)