They only need power if you want to get pretty loud. At normal listening levels, most systems use very little power, no more than a few watts in some cases. You don't start running into major power issues until after you've crossed the limits of sanity
The issue you'll run into then is usually clipping which can be hard on all your parts, and mild clipping is sometimes hard to catch unless you know what you're trying to hear.
As long as CaysE keeps in mind the audiophile unit isn't the greatest platform to base a system around and keeps the volume reasonable it will run the Kappa's just fine.
CaysE, the time correction covers specific output channels on most head units. One for each door and two for the subwoofers. The beauty of the setup is that you can use each of the six channels to work for the individual parts of your components. My particular head unit can be switched to 3-way mode which makes setting thngs a bit easier. Since the head unit also has a pretty robust active crossover (as most do these days) I don't even use in line crossovers with my system. One you get a new head unit, you can take the crossovers that came with the Kapas and use them as door stops. They are made for the masses, a happy medium that will work well in most cars, after you get a new head unit you have the option of fine tuning them yourself and there is a lot of improvement to be found by simply exploring the crossover point.
This is the setup I am using. The numbers aren't exact, I can't remember what everything is set at in the car
EDIT: I forgot to save a layer in photoshop, oops. The circles and rectangles on the side are speakers, the large one being the sub. The top rectangle is the head unit, and the lower two are amplifiers.
The head unit sends a signal through the RCAs to my two amplifiers (one 4 channel for the midrange and midbass, and one 2 channel for the tweeters). The time correction and crossover points are set through the head unit, so all the main speaker amplifiers have to do is amplify the signal. The sub amp has it's own crossover point, set at the amplifier, as well as it's own EQ and time correction settings.
The beauty of built in EQs, time correction and crossovers is that you can adjust them from the listening point, instead of going back to the truck, turning a dial and hoping it worked right but never being sure. In a perfect world I'd be running a much more robust active system like an Alpine PXA-H701 and the faceplate to run it, but that's getting way up there in cost, and I'm poor so screw that