All these men were under the supervision of their father for the music of the temple of the LORD, with cymbals, lyres and harps, for the ministry at the house of God. Asaph, Jeduthun and Heman were under the supervision of the king.
NIV
All of whom were [in the choir] under the direction of their father for song in the house of the Lord, with cymbals, harps, and lyres, for the service of the house of God. Asaph, Jeduthun, and Heman were under the order of the king.
AMP
All these were under the hands of their father for song in the house of the LORD, with cymbals, psalteries, and harps, for the service of the house of God, according to the king's order to Asaph, Jeduthun, and Heman.
KJV
Along with their relatives – all of them trained and skilled in music for the LORD – they numbered 288.
NIV
So the number of them [who led the remainder of the 4,000], with their kinsmen who were specially trained in songs for the Lord, all who were talented singers, was 288. [I Chron. 23:5.]AMP
So the number of them, with their brethren that were instructed in the songs of the LORD, even all that were cunning, was two hundred fourscore and eight.
KJV