So when I'm playing my music all of my electronic and rap songs sounds clean but when I switch to something like Metallica or zz top I get some distortion.
I usually keep my EQ on flat but even if I change it to the rock EQ it sounds bad.
I have the manually adjustable EQ and need to know which frequency I move to turn my treble down too.

http://www.decibelcar.com/articles/43-theory-and-physics/141-treble-hertz.html

should help you understand what all the equalizer settings do.

you using auto sound leveling feature? not all mp3s are the same when it comes to output levels.

I'm using SoundCloud and spotify
Auto sound leveling is on
I just spent about 45 minutes messing with the frequencies and some other settings, everything sounds amazing so far except 1 song lol
Thanks for your help!