Question About Impedence...

Since you show the speakers connected in series you would add the individual impedence of the two speakers together to get the total. (i.e. 2 - 8 Ohm speakers would net you 16 ohms.)

Most amps deliver a signal that will operate speakers rated from 4 to 32 Ohms. fishin' is correct about wiring speakers in series which is a good way to keep them in sync so that the speaker cones are pushing and pulling air in unison. If you wire together two 16 Ohm speakers in this way, you'll still likely be able to drive them. I would go for fishin's instruction.