Like if the minimum setting is 4 volts then does it produce all of its power at that setting or do i have to turn it to 1 volt to get all of the power ??
the gain adjusts the input sensitivity to match the pre-amp voltage of the HU.
If your HU is 2v, then somewhere in the 1-2v range on the gain will get full power out of the amp (1-2 because the HU won't actually produce 2v until it's at or near full volume). If your HU is 4v the gain should be at the 3-4v range.
Setting the gain "louder" (lower voltage) won't produce more power. The amp will just reach full power at a lower volume setting on your HU, and going above that will only clip the amp and sound awful
