Do you have a rack of equipment between the speakers? That will affect center image and height placement of a singer. The components will reflect sound to your ears, anchoring the vocals at their level. If you don't, then good, use that center space to tune the imaging with acoustic treatment. Not just absorbant treatment, but diffusive, or a combination of the two. Check out Michael Green's "Room Tunes" products for an example.
Singer sounds lower than ear level, help raise it
My speakers are currently on stands and the tweeters are at ear level. But still i find that the sound of the singer comes from the center of the speakers but it is lower than my ears. Her mouth sound like its only 2 feet from the ground. Is there anyway to raise the focus of the singer higher? thanks