I would like to spend under $100 USD

I think I am going to go with the Mad Dog by Mr. Speakers. I wanted to ask an additional question: amplifier or no amplifier? If so, what is the best combination of low price and portability?   Thank you everyone for helping me out! 

do the sennheiser hd600's have a lot of sound leakage? 

Hello,   I am hoping someone could help me out in finding a pair of headphones that would best suit my needs...   1) Price Range: $250-350 2) Over-Ear, Closed (maybe Noise Canceling?) that are good for all types of music... I listen to a lot of progressive house as well as a lot of...