How do the beats studio's compare to these?

How to do the beats studios compare to these. Ive read that the beats suck every where and thats the only pretty good head phone i have every listened to. 

I am looking to get some headphones. I am kinda new to all of the headphone gamea. My dad has some beats studios and gave them to me. I am looking for something better in the 400-200$ range. I am looking at the ultrasone pro 900's but I am wondering if there is something better. I listen to rap...

Thanks, for the ultrasone pro 750 should i get a portable amp? If so which one?

Hi guy, I am looking for some head phones. I listen to mostly hip hop and rap. I was looking at the ultrasone pro 900's. I would like the head phone to be under 400$ and would i need a portable amp?

and im on an iPhone.

I was looking to buy the ultrasone pro 900's. I was wondering what amplifier would be good, or if i even need one. I want it to be under 150$ and one that i could carry where ever i went.