Yesterday I confirmed a suspicion: when the music is interrupted because of a notification sound (message, alarm, calendar), it doesn't resume. That's a bit of a bummer.

And to everyone suggesting bass/treble instead of a full EQ: you realise that's not actually significantly easier, right? There's two components to either solution: the UI, and applying actual filters to the sound. The UI is just about as complex for two knobs, three, five, or nine. (Ok, more than 9 in the n9 screen would be a problem.) And the applying effects is the really difficult part; as eviljazz has said, the backend he's using for playing the sound doesn't support EQ, so at the very least that would mean writing an adapter for a whole other backend, and based on what we've seen for other players, it seems an implementation capable of an EQ would eat your batteries a lot faster (since you can't let the hardware decode the music). So again, in that case, 2 channels or 9 would be about the same effort.