Listening to the Rocketboys – both on their new record, Build Anyway, and onstage – you get the sense that their sweeping, anthemic rock sound could fill an arena someday.

First, though, they need to work on filling the Riot Room. Judging from the curiously sparse crowd that greeted the Rocketboys there Sunday night, not that many music fans yet know who they are. If justice is on their side, and they continue to deliver strong performances like Sunday night’s, that will change.

This Labor Day Eve show featured two odd takeaways. First, the Rocketboys were the only one of the lineup’s four bands that didn’t have “Bear” in their name – something that was naturally worthy of repeated onstage references from the night’s performers. Second, the crowd size peaked during the set of the second band, local act Bears and Company. Less than probably half of that crowd stuck around to see the top-billed, out-of-town acts, Austin’s Rocketboys and Orlando alternative-pop act Bearcat. Those who left not only missed the two top-billed acts; they also missed the two best.

With five players and their grand, atmospheric sound, the Rocketboys seemed confined by the Riot Room’s stage, but they made the most of their surroundings. Eight of the 12 songs they played during their approximately 50-minute set appear on Build Anyway, released in early June. Singer/guitarist Brandon Kinder was in fine, emotive voice, hitting the dynamic shifts that give the band much of its allure on record. His bandmates provided able instrumental backup and harmony vocals to produce a sound that often calls to mind Coldplay with more guitar and less piano (although keyboardist Justin Wiseman factors heavily into the group’s sound as well). An early highlight came on a performance of the half-lifting, half-haunting 2010 track “Brothers,” with all five members joining in on the chorus: “If you’re going down, then we’re going down/Oh, we’ll all go/As brothers.” Kinder starred on Build Anyway standouts “Time is a Devil,” “Bloodless,” and “Marching to the Palace,” all of which allow his voice to soar.

Perhaps the most impressive thing about the Rocketboys – given the self-indulgence you often get from bands that go for ambience – is that they keep their songs tight, focused and unwandering. With a set that featured maximal music and minimal chattiness, they played their piece and got off the stage, leaving the audience to imagine that there can be more where that came from. Hopefully, there will be – and next time, there will be more ears around to hear it.

Each of the three openers played just a handful of songs, but Bearcat, featuring vocalist Renee Yohe, made the most of an abbreviated set. Yohe — backed by bandmate Sean Sheahan on guitar and members of the Rocketboys on keys and drums – was sick, but still brought a strong yet sweet vocal presence to a set of minimalist pop tunes. Highlights included an original called “Salidade” and a surprising cover of Gorillaz’ “Clint Eastwood.”

Bears and Company entertained the biggest share of the crowd with a hard alternative/power pop sound, but the most notable facet of its performance came courtesy of its screamo side; when shouting hoarsely through his vocal passages, guitarist/secondary vocalist Alex McClain generated more spit than an overheated St. Bernard. Fellow locals BearFace kicked off the musically diverse show with a set of laid-back songs with a ’90s alternative feel.

Rocketboys — set list:

1. Marching to the Palace
2. All the Western Winds
3. Brothers
4. Time is a Devil
5. Walking on Fire
6. Sights and Sounds
7. Bloodless
8. Carry Me
9. Someday soon
10. Rare Triumphs of Love and Fortune
11. Hallowed Ground
12. The Best

Photos by Nicole Chaikin