Let's nip this in the bud right now: just because an electronic device has two different embedded circuit packages in it does not make it "dual core". I'm going to find it pretty irritating (admittedly, for no good reason) if "dual core!" stickers start getting slapped on every new consumer gadget. In this case it's a particularly bad example: having a digital/analog converter outside the general-purpose processor is completely normal and unremarkable. If you were building an mp3 player out of off-the-shelf components (that weren't specifically designed as integrated solutions for building mp3 players), you'd end up with a separate DAC quite naturally — it's not exactly a premium feature. And you'd really be a dope to call such a solution "dual core".

But if you insist on it, you might as well call the iPod sextuple core. Check it out: it's got a genuinely dual core ARM processor, a DAC, a firewire controller, an LCD controller and (not listed on that page) I believe the video on newer models is handled on a separate IC. What does all this mean? Nothing, other than that — surprise! — electronic devices aren't magic boxes. They have pieces inside of them. Unless you know what they are, counting them won't tell you very much about which gizmo to buy. I suggest sticking with the traditional "shiniest" heuristic.