From left, David Murray, Peter Ellefson, Matthew Guilford and Stephen Dumaine of the NSO play on stage at the Central Union Mission in Northwest Washington on Tuesday. (Clinton Yates/The Washington Post)

Before the show began, Peter Ellefson was changing out of his snow boots and into some more comfortable shoes by the side of the stage. Like the crowd he was getting ready to play for, he was coming in from the cold and first needed to settle in. Except, for much of his audience, this is what they do every time they come to Central Union Mission, because this is where they live.

As part of the National Symphony Orchestra’s “In Your Neighborhood: From Brookland to NoMa” series, three trombone players and one tuba player formed a quartet to play in front of the mainly homeless crowd before lunch Tuesday. The informal setting provided a humbling look at how the power of music can make even the most marginalized members of the community feel like they belong and are a part of something larger, even if their everyday lives don’t indicate such.

Before the program began, Stephen Dumaine, the tuba player, took questions. The crowd seemed as curious about the lives of the musicians, as people, as much as anything. How good is the pay? Do you travel to other countries as well? Have you ever met any famous musicians? Dumaine mentions Nas as one of his favorites to have had the chance to work with.

The show itself was personal, intimate and to some extent revealing. Before each piece, a different musician would tell a short story about not only the song but their connection to it. Before his solo tune, “Elegy for Mippy II,” Ellefson said: “It’s good to be here. It’s nice and warm in here. I look outside and see that it’s not so warm out there.” The crowd nodded in agreement.

This should be fun.

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The rest of the event played out in similar fashion, switching back and forth between loud “right on!” comments and people enjoying the serenity of the moment with their heads bowed. There was enthusiastic applause after each song. The selections ranged from traditional orchestral music to other more “funked up” jams that got heads bobbing. “Trombone Institute of Technology” — a song titled after a joke by students at the Eastman School of Music, in the same New York town as the Rochester Institute of Technology — was particularly popular.

Matthew Guilford, who plays the bass trombone, also known as a “tuba on a stick,” picked the music. “Of course, it’s a complete 180 from playing at the Kennedy Center. But it’s all about the adaptability of the music. That’s the universal thing. For us, we’re still playing the same kind of music, we’re still doing our thing, we’re just doing it in a different kind of place,” Guilford, 50, said. “I try to cover the gamut, from what we do as an orchestra, and select some pieces that are from that repertoire. [Then] put some more modern things in there, some things that are rock and jazz-oriented and go back to some of the roots of trombone. You know, back to the 15-1600s as well.”

One man, who sat in the front row, could barely contain himself when the set was over.

“I loved it. On the real, for real. The reason that’s so is because, my son was playing [in a band.] He played in high school. I heard him, but I never heard him real well. He was the only trumpet player in [his] high school, in Knoxville, Tennessee,” Charles Phillips, 51, said. “He loved it. And he always tried to tell me how good and awesome it was, you know what I’m saying? And then, I hear these guys, and I believe.”

Which is exactly the program’s goal, no matter who gets to be a part of it. Various groups will be returning to the mission on Thursday and throughout the weekend, but there’s an entire slate of programming in NoMa and Brookland that will give others the opportunity to see the orchestra outside of its usual box. Friday, local artist Christylez Bacon is teaming up with electric cellist Wytold to do some collaboration pieces with the NSO at EchoStage, for example. The event ends with the entire orchestra coming together for a performance at Catholic University on Monday.

They’re four years into the effort, and it seems to be going well. “I do think people are connecting,” Warren Williams, the NSO’s community relations manager, said Tuesday. “When people feel like they can touch it and feel it and see it, it becomes real and then it becomes personal. … We have a lot more work to do. We want symphonies to live forever, and this is one step in hoping to make that possible.

After the music had stopped and all the instruments were put away, the four guys who’d just entertained the room with their dazzling musical talent showed just how this program goes well beyond music. They sat down with the mission-goers, at the very same tables, ate the very same food from the same cafeteria, and talked.

Just like friends having lunch on any other day.