On Monday at the Teatro El Circulo in Rosario, Argentina, the NSO played an unusual program: rather than mixing it up with a concerto or a shorter piece, they offered two symphonies — the Beethoven 7th and the Tchaikovsky 5th — back to back. “That will be a true test of our stamina,” said Marissa Regni, the orchestra’s principal second violinist, before the tour.

One of the notable features of a tour is that the musicians play the same pieces over and over — including, in this case, some of the chestnuts of the repertoire. (Nurit Bar-Josef, the orchestra’s concertmaster, observed that the Tchaikovsky Fifth is so familiar to musicians that if “you wake us at 2 a.m., we can play it.) I asked a few of them how they felt about the two symphonies on the South America tour program, and whether Eschenbach played them any differently than they were used to

Above: What do musicians wait for in a piece they know like the backs of their hands, playing it over and over on tour? Nurit Bar-Josef, the NSO concert master, falls for the second-movement horn solo in the Tchaikovsky Fifth (here, Leonard Bernstein leads the BSO). “I know it’s cheesy,” she says. “Call me a romantic; I’ve always loved that melody when the horn comes in. It’s such a great moment.”

“There are definitely several spots where he’s doing things that are much different,”said Bar-Josef, “mainly in tempo. For the Tchaikovsky, he came with his own bowings, which I think actually came from Philadelphia. It can make it feel like a different piece when you’re used to playing something one way; something as mundane as a bowing can make it feel different. I don’t have a problem with that, it makes it feel new... It flexes our muscles to be doing something that’s not quite comfortable. He’s going more for a sound; he doesn’t care if we have to struggle to get it.”

“He did the Beethoven like every movement was attacca,” said Regni, using a musical term meaning there is no break between symphonic movements. “He says he wants to do the same thing with the Tchaikovsky... It’s nice to segue immediately into the next movement, whether there’s tension at the end of a movement and you want to release it... [or] you want to hear a different key. He wants to tie it all together. I liked, in the Beethoven, how it flowed from one movement to the next. I really liked the slow movement, how he just built that up; that movement has such sorrowful [overtones, and] he just stretched that out.”

Eschenbach himself is clear about why he wants to use the attacca. “I always try to get very, very deep into the thoughts of the composer,” he says; “into the sound of the composer. [With] Tchaikovsky, you have to deal very much with the density of sound, the expressivity not only of one line, but the whole sound development.” He adds, “I do with this piece the same way I do with the Beethoven Seventh; I make it really attacca of the movements, so the very dark e minor chord, the last chord of the first movement, goes into the d minor chorale [of the second movement], out of which the famous horn solo emerges.” He enumerates the way each movement yields to the next; “and so it is one cosmos, this piece.”

Do they ever get sick of playing the same things over and over? Lambert Orkis, the orchestra’s pianist, thinks the repetition is “good, it’s healthy.” Orkis is also a collaborative pianist with some major stars, and has partnered the violinist Anne-Sophie Mutter for more than two decades. “Anne-Sophie and I, in 1998, spent the entire year playing Beethoven sonatas,” he said. “You kind of climb that mountain every night. That music is not automatic. It shouldn’t be automatic. If it gets to be automatic, you’ve got a different problem to deal with. Hopefully, [you’re] finding new things to say. Even if not, you’re playing in different conditions.”

As for the Beethoven 7th, “I love the entire piece,” Bar-Josef says. ”If I had to play that every week, I don’t think I could get sick of it.... There’s something pure, yet passionate, yet you can be kind of rough with it. And there are so many great moments. You turn the page, and there’s always something I really look forward to.”