And will FiiO E7 Portable Headphone DAC Amplifier improve the sound and volume if i decide to go with the Denon d2000?  Best regards

Thanks a lot for all the help! After reseach I have decided to go for the D5000 or the D2000. I depends on the sound quality difference. Is it hearable when listening from the Iphone?  

Can the d5000 be used without portable amp? And if so, can they play loud enough? Thanks again!

Thanks so much for all the replies! Which ones would you consider the best for portable use direct from Ipod. Denon d5000 or the b&w p5?

Hi!   I am looking for new pair of headphones! I mainly listen to jazz(coltrane, davis etc) I plan to use them with my Iphone 4 and my budget is around 500 $. They should be able to play loud and without using portable amp. I´ve considered the Pioneer hdj-2000?    Help would be...