1 Chronicles 15:27

27 Now David was clothed in a robe of fine linen, as were all the Levites who were carrying the ark, and as were the singers, and Kenaniah, who was in charge of the singing of the choirs. David also wore a linen ephod.

The ephod was a sleeveless vestment worn by the high priest. In this verse, King David, who is not the high priest, nor was he a Levite, was wearing the ephod and a robe of fine linen. The Levites and the choir director were also clothed in linen robes. What does all this signify?

1. David was a shadow of Christ (OT prophet, priest, and king)
2. The Levites were doing the work of the Lord (and were dressed like it)
   
3. The choir director (Kenaniah) was also a religious leader, clothed like a priest, because he was also leading worship since he was in charge of the singing of the choirs.