you shouldn't have to crack the case and set gain pots.
helix dsp software -> dcm tab -> pc-tool configuration: ensure source level control is enabled.
helix dsp software -> io tab -> every input should be 0db (control is next to the input label on the left).
your per-channel outputs shouldn't be above 0db if possible and there shouldn't be any overall EQ boosts above 0db until you're more familiar with tuning.
my experience with the helix pro mk2 and helix mini:
- you can go up to +5db on input levels without adding any floor noise/hiss
- you can go +2-3db on the output levels without having clipping problems, doesn't seem to impact floor noise/hiss.
should be able to set amp gains at least 1/4 of the way up without introducing noise.