That's definitely an option. I've got a 160GB iPod Classic, so the big hard drive and the accessories that I can pair with the iPod keep me locked in. If I were to get another brand of music player, I couldn't use my external DAC or have full control from my car's deck.
I guess my point was that you can improve the sound of any portable player with a DAC and an amp. (Maybe not as easily with a nice HiFiMan player...) And buying those accessories might be a better value than replacing a functioning iPod with a better player.