I used 12 and 14 gauge wire for various speakers, mainly because it was available and met my criteria for in-wall or under-carpet use, etc.
There's a tendency to shy away from smaller gauge speaker wire. However 16 gauge wire is rated for 13 amps at 115VAC and 1560 watts, *continuously*. It's safely used as AC extension cord for fairly high wattage devices. It seems 16 gauge wire could carry much lower loads typical of speakers. Those likely average around 1-2 watts with very brief peaks around 100-200 watts.
