System Set Up Help

Hi everyone. It has been a long time since I have installed any car audio equipment other than a head unit replacement or speakers. I am installing (2) MM651 and (2) MM691 speakers in my boat (no subs). They are powered by a Polk D4000.4 4 channel amp. My questions are what would be the proper amp setup for this scenario. I was told that because these speakers have factory crossovers that I should set the amp to full range and simply adjust the gain. Is this correct? If not can anyone give me suggestions for the amp settings?