Home theater and 2 channel setup from same speakers?

Is it possible to have a home theater mutli channel setup going to the same L/R speakers as a 2 channel system?  Some kind of A/B box? 

I currently have a home theater 5 channel setup.  I would like to add a tube based system and some new speakers.  The room I'm in could probably support both sets of L/R speakers but I was curious if I wanted to downsize speakers, is it possible to run a AVR and tube integrated amp without physically moving cables and such?