I am considering buying the DT1350. Do I need an amp for these? 

I'm thinking about going for the Beyerdynamic DT1350, what I'm wondering is do I need an amp? My friend has a pair of Beyerdynamic DT770 and when I tried those on, I really felt that they needed an amp. 

Judging by the price of the PX100-II I'm thinking the sound isn' that good, and they kind of look like the sound leaks a lot. My budget is around 200-300$

Hi,   My Bose OE just broke, I've only had them for 2 years so I'm pretty disappointed as I have been very satisfied with these headphones.  Now I am looking for new ones, I'm looking for some great sound obviously, but most importantly these will only be used while outside and so they need...