Think the subs are wired up correctly for what you have. The filters will help.
You can try to move the subs out next to the mains, or even (gasp) stack them. In your room, stacking might help.
Can you use your turntable with the sub right there? It looks like a very crowded room. We are here to help you spend thousands of dollars. Might be time for a better rack/cabinet setup to get more room.
BTW, you NEED way more vinyl.