Aperiodic does more than just the impedance. It still has an affect on damping. I have yet to believe clarity can exceed it with just a sealed design. It isn't hard to try. If that box is 1ft cube, you need two. Then stuff a bit to taste, and to avoid any peaks.
You cannot see some resonances unless you use only no feedback equipment to look. They are not nodes in the room that I refer to, but rather patterns that develop across and around the baffle, which can be the whole box depending on frequency.