What sandm said. It sounds like that's how they're run now. That's a common practice that most use to do that, but to be a little more specific run the four cabins in parallel off two channels. In other words run the port two speakers to the left channel + & - and the starboard two speakers to the right channel + & -. Just twist the pairs (+&+, -&-) together and connect at the amp.

You could run the bows off the head unit as you mentioned and the four cabins to each channel but the bows would be underpowered and really un-noticeable, it all depends on what you want.