is it better to buy a decent headphone+amp or to buy a good headphone terus?

Your rig - laptop, ipod, ps3, tv, phone (for all purpose laa)
What type of usage - Music, Movie
File format used in your source - Multiple sources
Genre of music you listen to - All kind of song
Headphone/ earphone type - No preference/ try and sendiri rasa
Budget - below 700

I see online some people say laptops don't have a good audio system. so a good headphone is quite a waste since can't use to full capability. and I think this applies to most of the rig I listed. Thus the reason I ask the previous question. the amp is to support the laptop audio and give a better sound.

So, which is better?

Tx for the recommendation. Where to find most of the headphones listed? I rather test it by my self than just buy based on reviews by people. not to say the reviews are bad, just personal preference.

in KL, where can i find most of the headphones in one place? malas laa nak jalan2 bnyk sgt.