I think your just using two preamps by going into the guitar input.
I think it would be better just using an analog input line in (balanced of course) at the rear.
The guitar inputs are designed to boost and match an instrument input, so those are preamps just the same.
It will work that way and it's fine...but I would try both ways and see if you get better results one way or the other but I think you will get better results in gain staging using the line in...
Give it a try and report back your results

Yup, microphone preamp to line level input. You don't really want to go into another microphone input unless you are doing it for a specific reason. Like to cop somebody's microphone transformer and/or preamp characteristic sound i.e. Neve, API, etc. Sometimes it can work in your favor sometimes not. I do it all the time but because of different reasons. Live recording presents its own obstacles.

I haven't decided whether a Neve preamp sounds better plugged into an API preamp or the other way around?
Mx. Remy Ann David