How to add center channel to stereo

     I use my all-tube stereo for the tv, too.  It sounds great, but the way movies are mixed, not to mention my aging ears, I could use a center channel for clearer dialogue.  Could care less about surround sound - or actually, I sort of dislike it.  Is there a good, reasonably priced way to add a center channel to an existing stereo? 
      I've considered just getting a sound bar (all those tubes cost money and run hot).