It's a Class D amp, so it's fair to say that it can't sustain any more than 1600W of total output power with zero overhead. (Assuming an amplifier power efficiency of 90%, available electrical supply of 120V, 15A). It might be able to briefly exceed this level, given enough onboard power storage (I.e. capacitors).
But this is all theoretical. The owner's manual doesn't actually say how much current the amp draws. 90% efficiency is quite high, and the amp might not be this efficient. This makes it impossible to say, with any degree of certainty, what the amp might be capable of sustaining.
Now people are going to jump on me here, but Crown does say that this amp is specifically for PA systems. I think that some might assume that this includes the broadcast of music. The manual doesn't say anything that I could find to resolve this ambiguity.
Obviously, a person talking and a band playing music are going to be quite different in terms of demand... and this will mean much different load being placed on the amp. Not to mention that you plan to use this to power a narrow band driver (sub).
Lots of unknowns, potential divergence in designed use vs. actual use, and being used in a very specific portion of the audible range.
Your guess is as good as mine. My advice is to call Crown and discuss your intended use and see what they have to say...