Trans-Siberian Orchestra began as a progressive rock-meets-classical music studio project in 1995. It wasn’t until 1999, after the release of TSO’s albums “Christmas Eve and Other Stories” and “The Christmas Attic,” that TSO founder, composer and lyricist Paul O’Neill put the show on the road.

TSO’s 1999 tour of a handful of U.S. cities whet the appetite for more TSO concerts. Guitarist and music director Al Pitrelli was there for those inaugural performances as well as the first TSO recordings.

“Promoters heard about this crazy bunch of Russians and an orchestra with pyrotechnics,” he recalled from a TSO date in Las Cruces, New Mexico. “They were flipping out. Everybody wanted a show.”

By popular demand, Trans-Siberian Orchestra — which began in New York City, not Siberia — is now two touring companies. TSO’s North American winter tour will reach 71 cities, including New Orleans and the Smoothie King Center on Wednesday.

The Smoothie King show will feature nine singers, a narrator, a seven-piece band and a half-dozen local string players. They’re performing TSO’s 1998 album, “The Christmas Attic,” on tour for the first time this year.

In the ’90s, Pitrelli recalled, “we were just in the studio making music together. We were like the Steely Dan of symphonic rock, or whatever you want to call us. ‘The Attic,’ our second album, got stepped over. We decided to bring it out this year. It’s been received so well, and we’re so proud of it.”

For “The Christmas Attic” tour, O’Neill added new characters, fresh narration and more music to the original. The show also features even more pyrotechnics than previous TSO productions.

Pitrelli performs onstage for “The Christmas Attic,” playing rhythm guitar and doing some conducting. Because the singers and musicians who perform the complex “The Christmas Attic” every night are so good, he said, they need only minimal direction.

Pitrelli and O’Neill are both from New York City, a culturally rich place that helped them become what they are.

“Growing up in the ’60s in New York and the city’s public school system, you were either on the football team or you were in the high school band,” he said. “I was too small to play football, so they handed me a trumpet. I was reading scores and playing in symphonic wind ensemble and the orchestra and choir all those years ago.”

Pitrelli and O’Neill met in the mid-1980s. They found they had much in common.

“Paul loved ‘Jesus Christ Superstar’ and Pink Floyd and Yes and Aerosmith and AC/DC and everything in between,” Pitrelli said. “He loved theater and Andrew Lloyd Webber — the same music I loved.”

O’Neill, then producing an album by prog-rock band Savatage, invited Pitrelli to add guitar parts to the project. The progression from Savatage to Trans-Siberian Orchestra came naturally.

“Paul gave me the opportunity to help create something,” Pitrelli said, “to write and arrange, to be there from inception to the downbeat of the show. It’s definitely my home. He let me tap into every musical thing I’ve accomplished and bring it to the table for TSO. He’s not only my producer, my boss, he’s one of my dearest friends.”

Next year will be TSO’s 20th anniversary.

“I don’t want to do anything else. Neither do most of the people out here. This is what they’ve dreamed about. As long as Paul O’Neill and Jon Oliva continue to write beautiful stories and the soundtrack becomes magic, dude, we’re on.”