Question

I see gain control for mix/line inputs 1-4, but what about 5-8? Is that controlled in the DAW somehow, or is it just accepting whatever level is coming in through the input?

Answer 1

Try using the UC control . Go into the presonus universal control and tap the 1810 a mixer should pop up on your screen. For you to set your monitor mix

Answer 2

Have the same question, how can I control at the entry level of the backside? I can't find it in Universal Control, I've been looking for a solution all day.

Answer 3

Line level inputs do not have a preamp stage in the circuit like mic inputs. Gain controls adjust the amount of work the preamp does to raise the level of your signal.  For line level sources, your input level is controlled by the source level. For example, the signal level (gain) for a synth running into input 6 would be controlled by the synth’s Output level (on the synth).  

TLDNR version- Gain controls the preamp level. Line level sources act as their own preamp. Therefore, no gain at the interface’s input.