@arnyk: I just bought the FiiO E5 on your recommendation. It gets the job done splendidly, and is nice and compact too. My only gripe is that if I've got it plugged in to USB power and it's not charging (i.e., the battery's full), it starts hissing quite noticeably. Which means I can't just leave it plugged in and forget about it; I have to unplug the USB if I hear the hiss, and then plug it in again when the battery dies. I suppose that provides a natural battery conditioning, but still, mildly irritating.
(My headphones are AKG K242 HD's, rated at 55 ohms IIRC.)
So thanks for saving me a bundle!