Anyone using UR28M with external Preamp?

Hello,

I run a Grace Design m101 mic pre into the Steinberg UR28M input 3 (m101 is single channel). I find this works quite well. I believe the inputs 3 & 4 on the UR28M bypass any “gain” electronics within the unit and fly direct to A/D conversion.
However, I still have issues totally understanding the internal Hardware mix/routing GUI within the UR28M (DSPMixFX).
I’d like to know concretely if I’m totally bypassing the internal mixing within the unit, as I prefer to handle that aspect within Cubase (C7.5).
Any ideas how to prove this out?

Thanks