one of the outputs is for the subwoofers, you will have to split the signal using a y splitter. 1 female to 2 male rca's.

I don't recommend putting tweeters in the dash at speed all you will hear is treble.

Thoughts on mounting the amps in the engine bay on the fire wall?
Is there anything wrong with running all 6 channels for the m6600 off of say the rear channel off the HU?

Sorry, had to do a little search, the m1700 is not a current product.
http://www.crutchfield.com/S-uLkvX7m...ml#details-tab
Looking at the input / pre-outs, I dont think he would need a y splitter between sub amps. Simply daisy chain with a standard patch cable?

Depending on how much sound reaches the ears at speed, trebble may be better than nothing. Since the tweets are separate, I would Install the mids and hook up some longer test leads for the tweets. Take it out on the water and experiment with different locations. Consider both at speed and maybe if you in the water behind the boat.
IF the tweets are a little too harsh at speed, consider adjusting the HU highs boost down so you get full advantage of the tweets extended range when hanging out around the boat?

Mount amps in the cuddy, as dry as possible. Also less heat and hopefully cleaner.

You can run all six channels off a single pair of HU outputs. Split using a Y, so channels 1-4 are receiving signal and select "sum" Input mode, according to the manual.

If you do a beach box,
I would use one pair for the sub outputs (did not see a specific sub output noted on your particual HU but might have missed something)
Use the Front channel for amp inputs 1-4 (Y split) for the 4 in-boats and Rear for 5 & 6 for the beach box.
This would allow you to turn off channels 1-4 while on the beach and conserve battery.

An onboard charger is a must with multi-battery setups. High output power supply/chargers like Kinetik or Iota can deliver the juice necessary to fully charge a depleted bank. Always charge upon retuning to dock, an alternator is not a battery charger.
Bonus, if you have a little 2,000w generator, plug it in, play all day at full voltage and run fans to keep the amps cool!

btw it takes 2 chargers one for each of my batteries 24 hours to completely charge my kinetics from dead. The hu does have a specific sub out, i also have a 100 amp power supply hardwired into the boat so when im on the beach i have the ability to fire up the generator!

I have a very similar setup (Baja 252). Have 3 Fosgate amps on a board under the v-berth, where the porta-potti was. One powers 4 10" JL subs mounted in an enclosure under the bench seat, other 2 amps power side speakers. They are 2 sets of Fosgate separates, 1 mounted next to the sub enclosure, another next to the driver/passenger leg area with the tweets mounted up high, and 2 sets of Clarion separates mounted in the gunnel storage and the entrance to the cuddy, with tweets on the dash. It's very loud inside the boat, but I've kinda trapped the sound inside. That's just how it works with these kinds of boats. Don't get me wrong, it's loud outside, but with 4K watts, it's gonna be.

If you want to sell a pair of the m770's - let me know

I have a similar set up with 5 Kinetk 2400 but my Iota 90amp works as both a power supply and charger. I have never let them run down but it only takes a couple hours for the bulk charge. Have never gotten more particular than that since the Iota is plug n go.

Since you have a a stereo shop, do you have experience with the 8 stage Ctek chargers that are supposed to be great at reconditioning a battery or one step this side of Jesus in reviving a dead battery?

http://smartercharger.com/products/b...multi-us-7002/

I would still use the Iota day to day but maybe twice a season recondition each individually. Batteries are too expensive to not maintain optimally!

i have the cket charger i use 2 of them one per battery! great charger it will charge any battery and it has a recondition cycle that will bring gell batteries back up to full! I sell them as well, also use them to recondition customers batteries. Let me know if you want some of them.

Im also an authorized kinetic dealer, they do have 3 year warranties but make sure that you do not ruin the label on the bottom of the battery be careful when removing them not to drag them (found this out the hard way!)