The answer to that one is "it depends" but typically, its best to get the strongest signal from the source possible, and turn down the preamps in camera as much as you can. Typically due to the fact that the preamps built into cameras are (while not bad in the C100's case) not the greatest.
That being said, it is possible to over modulate the source if the transceiver/receiver is too hot. Just kind of one of those situations where you need to spend some time playing with different combinations of settings to see what sounds best.