I think that would make a pretty good setup, but to fully consider your options, I have two questions:
Why no subwoofer?
If you are in an apartment or like to watch movies late when your kids are going to sleep, it makes some sense to not have a sub, The Aperions have marginally good extension for music, but they will definitely come up short if you like to feel the rumble of a low flying space cruiser or the stomp of a dinosaur.
How big is the room you plan to put this in?
If it is a large room and if you like to crank it, you will definitely need the XPA-3. However you Pioneer appears to have a decent amp section. Note that Tom Andry reviewed these speakers using a 100W, 7 channel receiver (rated for 8 ohms).
I'd suggest you buy the speakers first, hook them up to your Pioneer, then evaluate what you need - additional amplification, a sub, both, or neither!
$600 will get you a pretty good subwoofer if you decide the amp is not required.