An alternative view...
First, DAP's cost considerably more than a decent PCDP. An iPod + iMod runs into serious money. And since they are based on hard drives with moving parts, and normally used in harsher outside environs, they are prone...no,
doomed to failure sooner or later, and will therefore require replacement (read: even
more money).
Secondly, something no one seems to talk about when discussing DAPs is the cost of maintaining your digital library. How much time do you spend ripping, storing, backing-up, & restoring your music (I consider my time valuable)! How much did you have have to spend on extra hard drive storage space? On a DVD burner & DVD-R's to archive it? What about charging your player? How many charging devices to you all have?
I'd rather spend my money on music, and my time listening to it. That's why I've gone back to my trusty old PCDP. I have one workhorse of a player with a very clean lineout for amping that I'd put up against the iMod, and a decent headphone-out when I want to go ultra portable sans amp (try that with an iMod). I have another player with an optical-out than can be used with a portable DAC+amp if I want. Can't get better sound than that.
I'm an album listening type guy. I usually listen to one CD on the train ride to work, and another on the way home, perhaps repeating. It's no hardship to carry two CD's. And if I buy a CD, or pick up a few at the library, on my lunch hour, I can listen to it immediately (also try that with an iMod). Batteries? A set of AA rechargables for normal use, and there's always somewhere I can pick up an emergency set if I forget to recharge the batteries (people sell them on the subways now).
Not saying one is better than the other. Just saying that not everyone has to use an expensive DAP, like the fine iMod, to get good sound. Often, good sound can be had for far less $$ if you are willing to look a little 'old school'.
Cheers.