I could have done something wrong. This is just the 16th photo that I have taken with my D600.
All I say is take more shots, especially RAWs if you are concerned about image quality in tests, as RAWs have full data, while JPGs only have very limited data like max 7 DR, while D600 DR at base ISO exceeds 14 (2.5 stops better than 5D3)!
In high ISOs, D600 clearly holds more detail even with aggressive noise reduction. In image quality (RAW processing), d600 clearly trounces 5D3... it is confirmed by many sources the world over, including empirical testing.