@Jim
Input gain should be enough to be above the noise on the analog channel in, and hopefully still with enough headroom so you don’t clip when the user yells loud.
After that you are in dBFS and the digital world, and the goal is to stay below 0dBFS.
AH has an 18dB headroom on top of their 0dB marking on the meters so you are safe to go all the way to AH0 and feel safe that sudden peaks will not clip.
Note that if you go to a DAW it will usually add more headroom so your signal will seem low in a PC until you raise it up 18dB or so.
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