I'm pretty sure it's the former.
Am I reading your sig correctly that your receiver is the VSX-919? I looked this up and the manufacturer claims 120 watts per channel. This is just less than half of the power available in each channel of an ADA1000. However, most likely the Pioneer claimed power is somewhat high. Anyway, that means most likely you could expect that an ADA1000 would produce a clean listening level somewhere around 3db louder (at least) as compared to your receiver alone.
I'm not sure that would be enough to make you happy. However, given that your receiver doesn't have a preamp out, your options to upgrade are limited unless you're willing to replace the receiver itself.
I personally have an ADA1500 driving the four channels of my LFR1100's, with another amp (Parasound) driving the centre and my two surrounds. Is this enough power? Most likely, yes!
Given your taste in music and knowing that you like it loud, I'd certainly recommend the "high power" version of the woofers in whichever Axiom speakers you get next!
