Then why would the cheap ass ones sound different?
Headphone amp matters, build quality matters, even the software matters (windows media player sounds different from Winamp too, with the EQ set to flat).
Don't forget that there's actually a small sound card in every mp3 player. There's a difference between sound cards too. The cheap 10 dollar sound cards do sound a lot worse than the expensive 100 dollar ones. Same goes for mp3 players.
You should really compare three mp3 players sometime if you can. It's not like I'm some mutated lifeform able to hear everything. It's just that I care. And by listening a lot I can now hear rightaway whether it sounds good or bad, but it's not like you can't hear the difference when you compare. It's actually really big.
The iPod sounds ratherthinnish with a lack of mid, the (at least the older) Sony Mp3 players have boosted high frequencies and I must say that my experience with most Creatives is pretty good so far.
Try and see. You will hear the difference
.