At times, the only sound that could be heard was O.A.R. lead singer Marc Roberge’s distinctive voice echoing off the cement walls of the auditorium amid a sea of nodding heads and dancing bodies. At other times the audience’s cheering and singing nearly drowned out the band.

Despite speculations that assigned seating would create a calmer and less involved crowd, the 1,625 members of the audience were not deterred by the rows of chairs.

“The fact that we’re in a theater doesn’t mean we can’t get crazy tonight,” Roberge said from onstage. And it got crazy indeed.

The band was introduced by U2’s “Beautiful Day.” As the chorus hit, intense white lights flooded the audience. All that could be seen was a mass of raised hands and beer cups as O.A.R. took the stage.

Though it was only 9 p.m., O.A.R. kicked off the show with the line “It’s 3 a.m. and I want to go to bed,” the beginning of “Night Shift.”

The band then tore through five previously released tracks, bringing out opener Pseudopod’s saxophone player Matt Keegan for extended versions of “Anyway” and “On Top of the Cage.”

Occasionally, the jams were unfocused and monotonous, with the same groove plugging away beneath increasingly chaotic sax solos being traded by Keegan and O.A.R. saxophonist Jerry DePizzo. But the band chugged on regardless, keeping the energy and volume as high as the spirits of the audience.

O.A.R. then slowed down the set with a new ballad, “A Tribute to James.” A lighter was raised, but was lowered after only about 13 seconds. Apparently, someone told the owner of the lighter that the trend died with the original Guns ‘N Roses.

Overall, the fivesome played four new songs, excluding the revamped versions of songs from previous studio albums.

The band walked off stage, but the crowd kept cheering. As expected, O.A.R. returned to the stage for an encore.

“We forgot to play a couple songs I think,” Roberge said, smiling.

The band then kicked off “Revisited,” an extended and revamped version of “Ladanday” from their album “The Wanderer.”

As the jam came to an end, the band regrouped and played their trademark closer, “That Was A Crazy Game of Poker.”

It wasn’t just a live version of the studio track or an extended jam version of the song. This rendition of “Poker” was a grand opus, complete with a transition to Bob Marley’s “No Woman, No Cry,” with yet another special guest — opener Marc Broussard — trading verses with Broussard and the audience.

The players were determined to prove that they deserved their self-applied label of “island-vibe roots rock,” and did not disappoint, especially with Broussard’s sweet, soulful vocals.

Sorry Cyclones, but your “Stephens Magic” wasn’t enough to upstage Broussard. His range and power were just too much for the fans who outnumbered him almost 2,000 to one.

Roberge seemed to agree.

“That boy can sing,” he said, shaking his head and smiling.

O.A.R. finished the encore with a surprise cover of U2’s “Sunday Bloody Sunday,” with a political precursor.

“Everybody’s got their own opinion, and that’s the beauty of America,” Roberge said to a crowd waving fists and peace signs. He went on to explain that he had a “buddy” in the Middle East who was “fighting for us.”

“No matter how you feel,” Roberge said, “we’re going to send out some positive energy.”