Ugh... Yeah sure, I met a lot of empty, plastic people listening to whatever MTV or other bullcrap will tell them is cool. Sure, I'm listening to metal (classical music, jazz, trip hop, rap. I don't care about genre if it sounds good to me) and I consider myself quite intelligent (or at least I never met anyone who would call me an 'ignorant', and people like to discuss with me on various topics), most of my friends still or at least at some point listened to metal, and I think they are intelligent as well.
But that does not mean it's true. I met several metalheads, who were just as dumb and empty as your typical high school jock, but instead of being plastic they were metal...
the bottom line is: it's not music that makes you intelligent, and never will be. True, sometimes listening to music may leave a spark inside you to for example make the music you love, and with that passion maybe you'll start your interest in other things which definitely helps your intelligence, but for the love of God, it can be love to electronic music, metal, rap, jazz, blues or even country.
It's your parents during the first stage of life, and then YOU. You are making yourself intelligent (or dumb), not music.