Some preamps are designed for both line level and mic level input through the same input.
Others aren't designed this way. Also even if they are designed to recieve both then the
design of the preamp might still influence the line level sounds.
Doublehelix recommended you'll have to read the manual.
Don't go for the cheap
Focusrite preamps. They sound like dog bawls! Get the DBX over the Focuswrong.