a couple of the previous posts mention the low, med, high setting on the dr-07.... to my knowledge these settings are when using the 'mic' input on the dr-07. when running 'line' in, these settings have no effect.
my rig is ca14 > ca9100 > dr-07, and i typically run thru the line in, full gain on the 9100, and the dr-07 somewhere between 04 to 06 depending on the SPL's in the room.
i've never had a clipping issue recording in this way.
correct me if i'm wrong about the low, med, high thing, but i thought that gain was just if running internal mics or the mic input.