How to add center channel to stereo

I'm not aware of any way to steer dialog to a center speaker without a processor. If you start down that path, you're going to be adding either a HT receiver or a processor and amp, as well as the speaker itself.

If you just want better dialog, you might try something like one of the ZVOX Soundbase or Soundbar models. They make 9 or 10 different models at different price ranges. They seem to be effective and very well built. Go to the ZVOX website for information on all their models.

REUBENT nailed it succinctly ..... full stop.

If you want to introduce a stand-alone CC discrete speaker, then it  is on a discrete encoded channel requiring a multi-channel AV preamp/ processor to decode. 

thanks. I guess I'll be proceeding along those lines.

Accuvoice processing on thé Zvox soundbar makes a very noticeable difference to the resolution of dialog.