Simple Stereo for 00 Air Nautique

Picked up an 00 Air Nautique last winter and need some stereo advice.

As it sits: All Factory Wiring
HU:http://www.kenwood.com/usa/car/marine/kmr-m312bt/
Cabin Speakers: Alpine SPS-M600 (x4).

I want to add a little bass and some power to the cabin speakers. I don't care to add any tower speakers. We aren't party cove folks and most of the time it's the wife, our little one, and maybe another person or two... That and depending on use and lake levels around here we might move to a v-drive in a couple years so I don't care to spend a fortune.

-For simplicity I'd like to run a single amp.
- Amp Recomendations?
- Sub Recomendations? I've had plenty of JL car audio stuff and have generally been very satisfied.
-The Speaker wiring from the factory is decent but nothing fancy.

- I have space under the observer seat for the Amp/ Sub. I've seen people put them under the helm in my vintage of Nautique but I'm not sure how easy it would be to relocate the PME and what not.

If the speakers were like our 95' Supersport there are four all somewhat centered in the main cabin.

.... I would wire each side in parallel so they're running at 2ohms.

Then find a three channel amp, if its hidden and out of the way, you don't need a marine one. 2 channels for the boat speakers, 1 channel for a sub.
For a sub, if you're just looking for a little extra, I suggest a single 12" in a properly sized box.

Here's a link to a post I made on essentially the same boat stereo build

http://www.wakeworld.com/forum/showthread.php?t=801814

One year ago to this day I finished it all up!

I just went with the L7 for my sub... Pretty solid for just ~$230 on good ol Amazon

Speakers are sort of spread around the cabin. One on each side of the rear seat mounted in the gunnel pad, one next to the observer seat, and one next to the drivers feet.

Parallel with a three channel is an interesting option.

I've been browsing 5 ch stuff as well.