@icegeek , this one is easy. Get a second sub and proper 2 way crossover. This will get your system stompin for sure. Everything else in the chain is minor in comparison. It is always at the back end of the system that improvements are most noticeable. If you pull 80 to 100 Hz away from your focals you will lower distortion and increase your headroom as much as 10 dB. That is twice as loud. Clipping will be much less common. You ALWAYS need two or more subwoofers. It takes at least two to smooth out room irregularities but the more the merrier. The bass in the room will be more even and powerful.
Forget the amp for now. You want the bass out of those Arias. The result will be even better. You would need an amp 8 times as powerful to get the same result. We are also not talking about just volume but clean volume. When your system can play at higher intermediate volumes (90 dB) super cleanly the experience is a lot more like being there.