I see. Thank you for the clarification.
Yeah honestly im not satisfied with beats quality, last time i was blind by the trend of beats. After I starting to enter the hifi world, i realize beats are waste of money, with that price i can get much more better product. Actually i wanted the Fiio e17 to enhance beats sound quality. But like u said it's better to find a better headphones first, amp come later.
After a few survey a while ago, I stumble upon Beyerdynamic DT 770 250 pro. that model almost fulfiled my requirement which is closed back, noise isolation, great sound quality, and the price are cheaper than sennheiser momentum. Dt 770 pro required headphones amp to maximum its performance. i think it will be good investment dt 770 pro pair with fiio e17.
I think I will buy headphones first, it will be a wasted if i buy FiiO e17 and it doesn't produce good quality sound with my beats ear buds.