The ceiling was raised, and a choral terrace was built onstage so the orchestra can perform Mahler’s third symphony.

In addition to the Bad Seeds’ playing, the new album has quite a bit of choral singing.

The second half of the performance is played by the Aurora Orchestra from memory, with the BBC Singers and National Youth Choir of Great Britain joining for a choral finale.

The result of their unlikely partnership, due Friday, is a lush yet gentle collection of songs rich with choral backing vocals and quirky chamber-orchestra textures.

“Orfeo,” with its poised 18th-century passion, could hardly be more different than the rhythmically angular modern choral writing in John Adams’s “El Niño,” which had had its dress rehearsal that morning.