Using Outboard Pres With The Motu 828, How do you set the optimum levels? Options

Hi,
I was wondering if anybody using the 828 with outboard pres knew of how to get the optimum signal into the computer. Do you set the levels on the pre first so that they sound right and then adjust the trim on the interface so that it doesn't clip? That seems to make sense to me but having the extra knob in the signal path seems a little confusing.

Any tips on recording drums this way? Do people usually employ a limiter to prevent clipping when recording digitally? I'm used to tape which is a little more forgiving in these regards. Thanks.

-Matt