i find the S9 a bit sharper, but the D2 is a much more open player, you can feel the differance in soundstage between both devices,
i have a D2, an S9 and a Clip
the clip is the most fun of the 3 players, the S9 is the better sounding of the 3, but i still like to use the D2 once in a while thanks to its versatility,
one thing, the Clip sounds good, but after a week using the D2, i went back to it, and it sounded bloated and muddy, i dont know, maybe its not all its cracked out to be,