the thing is that the D2 has 2 major advantages, the 36mW per channel (or 76mW combined if you like it better), making it able to push decently most IEM, small and medium sized headphones decently without amping, just make sure you check the impedance on youe headphones first to make sure you dont push it too hard,
the other thing is that the clix maxes out at 8gb currently, the cowon D2 does only have 4gb internal storage, but has the SD slot, which currently supports 8gb cards and there will be 16gb cards around the end of Q3 start of Q4 and should be decently priced for xmas, so, the D2 will be able to reach 20gb, which isnt that bad, the only player giving you 20gb at that size is the archos 204, which is nice and cheap but has a horrible control sceme and is limited in features,