Being that I read posts from a nontechnical background, I always appreciate a metaphor...
So maybe if you're speaking into a megaphone, your voice is the gain and the megaphone is the amplifier (volume). If you're yelling into a small megaphone, you're working too hard and the sound becomes fatiguing. If you speak very softly, the megaphone needs to become exponentially larger to increase the volume of your words.
Am I close?