What distinguishes one top-rank orchestra from another? For the Chicago Symphony Orchestra, it’s long been the brass.

For decades, the “Chicago brass” has been prized for its majesty, virtuosity and sheer power. From its modern-day origins under Rafael Kubelik and Fritz Reiner to the brawny blasts of the Georg Solti era to the subtler approaches taken by Daniel Barenboim and now Riccardo Muti, brass has long been central to the ensemble’s sound.

“The Chicago brass: This was a way of referring to the Chicago Symphony even when I was a young student in the conservatory in Milano,” said Mr. Muti, 78, who is in his 10th season as music director.

Mr. Barenboim, Chicago’s conductor from 1991 to 2006, said: “When you become music director of a great orchestra, you have to be able to recognize what belongs to the orchestra: what is characteristic — what is the stomach of the orchestra — and what is the influence of other conductors. And the Chicago brass was part of that stomach, of that unique way of playing.”