[CHaqmol]

Hi everyone Between these three models : Senn HD 238 - 438 - 448 which one is a better choice for me since i mostly listen to jazz-jazz fusin-60-70's rock-classical and world (also,do i need an amp?) thanks

 

[elemoor]

Would you like to use them outside? Do you prefer the circumaural (over-ear) or the supraaural (on-ear) type?
 
Do you really have to choose from the headphones mentioned above? They are not that good for the price. If you can, check out the Shure SRH440 and the Superlux models HD660 (closed) and HD330 (open). In my opinion they are all better for all types of music than the Sennheisers you mentioned. (Currently, I use a HD660 and a HD668B for the same genre.) The Superlux headphones have a bit "V" shaped characteristic, while the Shure is more balanced, however it is stronger in the bass a little. I prefer the Superlux models in this price range.
If you choose the Superlux, you'll need an amp. For the Shure, it's not necessary. If you have to choose from the Sennheisers, you won't need an amp.

 

[XxDobermanxX]

For the Genres you mention go for the sennheiser HD 448 but why not go for the newer version of the HD 448? last time i checked the HD 448 price jumped to $100, if you can get it for $60 bucks and under go for it but if its over $100 go for the newer HD 449, its a pretty low impedance heaphone so you will not need an amp.   
read this review it compares the hd 449 to the 238
http://www.head-fi.org/t/596050/the-new-sennheiser-hd-449-review-feat-hd-238-hd-203-the-final-verdict