All of Home Free's performances from The Sing Off in the order that they were aired. ⬇︎⬇︎⬇︎⬇︎⬇︎⬇︎⬇︎⬇︎ Song Time Code Below. The fourth season of The Sing-Off premiered on December 9, 2013. The number of a cappella groups was decreased from sixteen back to ten, resulting in a new format. The third season of The Sing-Off premiered on September 19, 2011. The number of a cappella groups was increased from 10 to 16, resulting in a new format. Please watch: Blake Shelton sings Lady Marmalade & Smokes WHAT?!?! w/ Christina Aguilera | The Voice . Season Premiere Wednesday December 17 9/8c. America's favorite a capella show is back! Just in time for the holidays, The Sing-Off returns as the country's top a.