Advice on this potential stereo setup

I am about to order the following equipment:

One pair REV10s
4 WS-650 speakers
One 12" sub- most likely JL 12w3 (single 4 ohm), will have custom box made for whatever sub

For amps, I already have an HT-4 that I was thinking of running the in-boats with, but not dead set on using it.
My other amp choice would be adding a SYN DX6 to run the REV10s and sub. The JL 12w3 sub was chosen based on the bridged 5/6 channel of 600w x 1 on the SYN DX6 needing a 4 ohm sub. Not sure if running the towers and sub on one amp will be taxing it too hard?

For the overall system objective, I'm looking for higher sound quality that can get loud but don't need an overpowering sub, just something that blends in some decent clean bass. Mostly listen to rock and country, occasionally hip hop/EDM.

I'd like some critique/advice on this setup, I'm also open to other amps and brands and any other suggestions or how better to configure this stuff. I don't have anywhere to demo the equipment so I'm just going to give it a try based on reputation and recommendations.

Thus far you have a system that is close to perfection. I would reach for total perfection by adding a SYN DX4 to drive the tower speakers and use the SYN DX6 on the sub and four in-boats.
I have zero reservations about the SYN DX6 ability to drive both the sub and towers, no thermal concerns, no power concerns. However, that doesn't mean that you can't improve on the plan with better power distribution. The sub and towers represent the greatest workload, not only in maxing out the power, but in running the lowest permissible load across all six channels. At some point it has to impact the power supply which feeds all channels and is current-limited. The common power supply is your most restrictive link within any amplifier. So by running the tower off a bridged SYN DX4 and re-distributing the SYN DX6 you have a more balanced scenario in all aspects....power workload....load impedance....thermal dissipation....

I am in the process of doing about the same system right now. Im going with a set of rev 10'S on a arc ks600.2 so I can add a second set down the line if I want. For the inboats our boat came with a ws HT6 and six 65I speakers so I pulled the amp and rewired the boat so each speaker gets its own channel. Then for the sub we went with the HTX2 for a jl 12x3v3-4 and built a ported box for it. Smallest system I have done so not sure what to expect.

Too bad you didnt have a 2 ohm 12W3, the new HTX-1 with its infrasonic filter is the cats meow for a ported enclosure.