Seldom, if ever, is the Mozart Requiem the work you sit through patiently while waiting for the main event to start.

That's no knock on the performance Friday by the Utah Symphony and Chorus with the University of Utah Chamber Singers, which was stirring, if a bit brass-heavy, under Thierry Fischer's direction. But on the other side of intermission lay Charles Ives' Symphony No. 4, heard for the first time in Abravanel Hall.

This magnum opus by America's greatest composer is bewildering and transcendent in equal parts. It's a grand existential undertaking that throws so many hymns and tunes at the listener — usually at the same time and in different meters — that it takes three conductors, leading different sections of the orchestra and choir simultaneously, to keep it on track. (There are also seven keyboards onstage, though they aren't all played at once.) The result, under the direction of Fischer, Barlow Bradford and Rei Hotoda, was glorious chaos that had some listeners heading for the exits midperformance and others insisting to their seatmates, "No, it was awesome!"

Utah Symphony

Mozart Requiem and Ives Symphony No. 4.

With • Conductors Thierry Fischer, Barlow Bradford and Rei Hotoda; the Utah Symphony Chorus and University of Utah Chamber Singers; soprano Joélle Harvey, mezzo Sarah Coit, tenor Benjamin Butterfield and bass Derrick Parker

When • Reviewed Friday, Feb. 17; repeats Saturday, Feb. 18, at 7:30 p.m.

Where • Abravanel Hall, 123 W. South Temple, Salt Lake City

Running time • 2 hours, including intermission

Tickets • $26-$84; utahsymphony.org

Steve Griffin / The Salt Lake Tribune The NOVA Chamber Music Series will give the world premiere of a piccolo concerto written for the Utah Symphony's Caitlyn Valovick Moore by British composer Simon Holt. Here Thierry Fischer, who will will conduct the premiere, works with the musicians during rehearsal onstage in Abravanel Hall in Salt Lake City November 1, 2016.
Steve Griffin / The Salt Lake Tribune The NOVA Chamber Music Series will give the world premiere of a piccolo concerto written for the Utah Symphony's Caitlyn Valovick Moore by British composer Simon Holt. Here Thierry Fischer, who will will conduct the premiere, works with the musicians during rehearsal onstage in Abravanel Hall in Salt Lake City November 1, 2016.