Focusrite Saffire PRO 24

Guys, I own a Saffire Pro 24. I use an Beringher MIC200 pre before the mic1 input. Must I set it to "Line" and give more gain to the pre than setting it to "Instrument"?
 
If line and Hi-Z does not have difference in gain, mic pre into either inputs can give no difference, so it is safe to plug into Hi-Z in case of absence of normal line input (for such interfaces). Difference becomes obvious for non-line signals.