Gintaras,
Before you had C3 did you listen to S9 flat or with EQ? because for me I always used EQ even back to my car audio days to earphones I used EQ with everything, I couldn't imagine using a flat setting, it was all about the bass and treble forming extreme V shapes. When I first heard C3 it was a little shock because flat sounds completely different, I was even skeptical buying a player that has no 5 band EQ, because I felt locked out. But when I heard C3 I knew there was something about listening flat, I could feel the vibe. I can imagine the increase in quality with C3 would be very obvious if you were coming from a flat setting, but not for someone who was addicted to EQ their whole life beforehand.
So that's another reason why I admire C3 because it was the player that changed me from EQing everything to listening on a flat setting. Now? I cannot use EQ with any DAP, it sounds terrible, messes up separation blows signatures out of proportion.