Well I gave them both a listen...
The Fuze sounds much clearer to me, goes a little in the direction of analytical. The C30 tends to warmth.
Both were compared flat, that means no eq-ing or BBE stuff. Well SQ wise both player are nice. Beseides the power difference, since there are 130mw. The C30 can even drive my Ultrasone 900, but the highs are cutting sharp :(, it is not possible to listen. With my Ortofon E-q7 the highs are decent from the C30, but the Fuze highs are a little better.
Mids are deffinitely better on the C30, kind of sound smoother than on the Fuze. Also the lows come much better on the C30. If I have to define deffinitely and much. deffinitely =20% and much =30%.
I use my Fuze with Rockbox, which is a definite plus, for me at least. On the other hand interface wise they cannot be compared, since the C30 just has a small oled display. Also it is possible to move quickly through the C30 menu, only small issue is that you have to wait every time you boot, to initialize the tf card.
BBE on the C30 is useless, IMO it worsens the sound, the C30 sounds best flat. Also there is a little noise in the background, but it is not noticable when playing even at low volumes.
All in all, I prefer the C30 soundwise, but the Fuzes sound quality is also one of the best available at the moment, not considering Hifimen adn other with integrated amp... Rockbox is just great, that is why I prefer the Fuze over all.

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Edited by RAFA - 7/8/10 at 1:59pm