[2][3] In June 2017, Kaplan released his solo debut EP Sage and Stone under the name Avriel & the Sequoias.

[4] Kaplan is Jewish of Ukrainian and Russian descent,[5] and has spoken of the antisemitic bullying he suffered in his youth.

He considers his earliest musical inspirations to be Simon & Garfunkel, John Denver, Crosby, Stills, Nash & Young, and Bill Withers.

Later inspirations include Iron & Wine, Bon Iver, Ben Harper, and José González.

[8][9] Before joining Pentatonix, Kaplan was already an accomplished a cappella artist, performing in the styles of jazz and opera among others.

[4][13] Kaplan joined Pentatonix in 2011, when original members Kirstin Maldonado, Mitch Grassi and Scott Hoying were searching for a bass singer and a beatboxer.

[22][23] His final show with Pentatonix was held at the Champlain Valley Fair in Essex Junction, Vermont, on September 3.

[26][27][28] On February 15, 2022, Kaplan formally announced his debut solo studio album Floating on a Dream, which was released on May 20.

[29] Its second single, "All Is Well" featuring singer Joy Williams, was released alongside the album's announcement on February 15, 2022.