I have a pair of Polk Atrium 4's in my cabin and a older pair of Poly Planar MA7500's I just mounted under the washboards in the deck. The Poly 7500's were in the cabin in the same spot as my Polks. The Poly's are just a tad smaller so they were actually a good fit in the cabin. My head just misses the Polks when sitting on the bench seat. I mounted a Clairion M502 unit when I first purchased the boat. The price has come down on these from when I purchased. It's a Bluetooth unit and no CD obviously. I was also able to purchase a mic that went with it as an option that I ran up to the roof of the cabin over my head where I sit at the helm. I can make and receive phone calls with it via Bluetooth and the stereo like in the car and the mic actually works very well. The one downside to the Clairion are the controls as they are a little not user friendly but the unit has performed well so far for 3 seasons. That said, I agree with the others based on what I have read and learned since I purchased the Clairion and when it dies I will likely replace with something like the Fusion in the pic below. Good luck