Just bought a new Moomba Mobius LSV and am considering adding additional tower speakers. It's our first wakeboard boat with a tower so I'm not too familiar with the stereo/speaker/amp necessities. I asked the dealership about adding 2 additional tower speakers and in the price quote they added an amp along with the speakers. Do you need an additional amp for ever new set of tower speakers you add? Right now they are installing 2 speakers and an amp but would I need another amp if I added 2 more tower speakers too?