Help with new system install

Hey Guys. I'm trying to get ready to install my new system. While reading the owners manual for my head unit on line ( Kenwood DNX9990HD ), I noticed that it had a "Gain" and "Slope" setting. Can anyone explain how I might use these ( or not use these ) for tuning my new system.

Thanks for any suggestions.

What will your "system" be?

Replacing everything in my Jeep Wrangler. New HU. Replace front component speakers with Polk Audio. Replace sound bar speakers with Polk Audio also. 4 channel amp for these speakers. Add subwoofer to rear with mono amp.
I've been researching how to set the gains on the amps. Along with setting the crossover filters. But I'm not sure what I need to do with the gain on the HU. Or the slope setting on the HU. Could someone steer me in the right direction please.

Thanks for your replies.