Ditto Paradigm Dawg's sentiment. In order to have proper panning from left to center to right and back again, you ideally want to have your center timbre match your mains.
Here's a small checklist for you to define so we can properly provide suggestions:
- What are the make and model of your mains (e.g. Infinity Interlude IL 10s, Boston Acoustics VR3s, etc.)?
- What are the size limitations of the space you're working with for your center (HxWxD)?
If you can provide these, we can provide a more suitable solution for you... -TD