More info is certainly better, so thanks for updating that table. Though, I can't think of a reason that a Rockboxed e200 would work with the dock and your c200 will not. Does the dock work properly with the SanDisk firmware?
A minor and tangential point is that the line out is only located in the dock connector. The 3.5 mm jack is a headphone jack, not a line out. So, it seems you're saying you can get sound from the headphone jack, but not from the line out.