Speaker Cables for Athena AS-B1

My Son just got back into setting up a system.  He got a Yamaha AS301 Integrated and a Pioneer turntable. His speakers which I gave him years ago are the Athena AS-B1 bookshelf.  The Yamaha is rated at 60w per channel and the Athenas are 8 ohm and 90db sensitivity and frequency response of 60Hz - 20kHz and a power handling of 125w.  A friend gave him some 16g in-wall wire to use.  I'm thinking he should at least get a 12g cable to get the most from his amp/speaker.  He does not want to spend a lot IF I can convince him,  Ideas?