he already has a deck with 3 preouts, so buying a new one would not gain anything. adding an eq would be one answer, but not real cost effective and not needed.

use one set of full range to feed the 4 channels of the kicker amp. use the sub output to channel 5 of the kicker amp. use the other 2 full range outputs and use a "y" adapter to split the 2ch to 4ch and power the jl with that, sending the same signal to all 6 channels(powering the 6 in-boat speakers). that would be the best way to do it, and how 90% of the stereo shops would do it. just be sure and invest in a quality set of cables. no radio shack here. I've done it before in an old car install. splitting the signal is the recommended way to do it in the jl manual.

by adding an eq, the only thing you will gain is the ability to take the one set of full range and send it to the multiple channels of the jl, allowing bow to cabin fading capability. if you think that's worth $289, then go for it. wiring it listed above would give you fading control of the sub and the tower/boat speakers independently, but would not allow you to fade the in-boat speakers. not a big deal imo, but it's personal preference. you could also add a volume attenuator inline with the bow speakers if you think they will be too loud. probably a $20-30 part.

the stumbling block here is that the jl needs 2 sets of inputs..


hope this helps..