The center image of a two-channel system is known as the phantom channel for a good reason. It is an illusion. It doesn’t actually exist.
Once you realize the center channel is completely dependent on setup, room, and speaker placement, it becomes a lot easier to purposefully do whatever it takes to enhance the palpability of your third channel.
One of the best techniques at center channel enhancement turns out to have nothing to do with speaker setup or equipment.
Place a vertically oriented picture or painting dead center of the front wall (the wall behind the loudspeakers) at about 6 feet high (its center should be human eye height).
That picture or painting will work wonders with your center image—not because it changes the sound, but because it helps you mentally focus that center image.
It is, after all, an illusion.