Power stage impedance

Newbie question I guess, but I searched the forum and found no fitting answer.
Suppose I want to control the behavior of the power input stage used with a class D amplifier (in my specific case I'm planning to use a MA12070p).
What can I assume the impedance load will be?
Knowing that, I could dimension a R-C network for, for example, set up a soft start.
One could argue that since you want most of the power to go to the speakers, you can assume that this is the main load. However, there is also a charge pump in the middle, among other amenities, and it all seems beyond my current understanding of (this kind of) electronics.
 
At this point I'm just assuming I will plug in an external 24V power brick. So I'd like to have protection against the usual stuff: polarity, power cable inductance kickback and so forth. Since I have to put some kind of circuit in there I though a soft start would be nice to have...