setting amp gains with over drive unit

i have a clarion cd player with a 4 volt output a audiocontrol overdrive unit a kicker crossover x3i and an alpine v12 mrv-f303 amp i want to know do i set all the amp gains to minimum or maximum the overdrive is plugged into the crossover and how do i set the overdrive units gain this is very confusing there are too many gains i dont want to overload the amps with too much voltage

Yes, amp gains turned all the way down.  To set the overdrive find a song that you would typically listen to, turn off your loud, set your bass to 0, set mid to 0, set treble to 0, disconnect the signals going to your amps so no sound is heard.  With the amp gains turned all the way down, restart the song and turn your HU all the way up to it's max volume.  Increase the gain on the overdrive until the appropriate led lights, then back the gain down a bit.    Adjust the kicker x3i crossover according to your specific taste.