He has also appeared at the Glyndebourne Festival near London, the Ravinia Festival near Chicago, and the Mostly Mozart Festival in New York City.
In 2011, Gunn was featured as a guest star in the Mormon Tabernacle Choir's annual Christmas concert before an audience of 80,000 in Salt Lake City.
The concert was broadcast on PBS and was released as an album in 2012 entitled Once Upon a Christmas.
In August 2015, Gunn starred in the world premiere of a new opera presented by The Santa Fe Opera.
It was Jennifer Higdon's Cold Mountain, based on the award-winning 1997 novel of the same name by Charles Frazier.
He has been dubbed a "barihunk" although as a play on baritone and hunk, he has said he prefers the term "hunkitone." In 2008, he was featured in People magazine's list of "The Sexiest Men Alive."Gunn was appointed a tenured professor of voice in 2007 at the University of Illinois School of Music, and in 2013 he was named general director of the Lyric Theater @ Illinois.
In 2012 the Opera Company of Philadelphia appointed him director of its American Repertoire Council promoting new American works.
His wife, Julie Jordan Gunn, who holds a doctorate (A.
Mus.
D.) in vocal coaching and accompanying from University of Illinois, was also appointed associate professor in collaborative piano at the University.