I went with the Infinity Reference 612M's. Installing them this weekend, so I cannot comment on the sound, however I don't think you can go wrong with Polk or Infinity in the cabin. For the Amp I have a JL 6 channel powering both the cabin and the tower. Kenwood Mono for the sub.
91' Maristar 210.
The bad thing about boats, is when they break, they break expensive.