Mandolin Orange performs at the Austin City Limits Music Festival in Zilker Park on Sunday, Oct. 11, 2015. (JAY JANNER / AMERICAN-STATESMAN)

“We’ll do our best to overpower the other stages by playing mandolin and fiddle at the same time,” Mandolin Orange’s Emily Frantz said as she and partner Andrew Marlin launched into an old-time fiddle tune during their early-afternoon set at the BMI Stage. Echoes of drums and bass drifted in from across Zilker Park — “I think our bass player went to the wrong stage,” Frantz joked early on — but it didn’t deter the focus of the acoustic duo’s tuneful performance.

The few hundred who gathered for the 12:45 p.m. set expressed their appreciation with hearty rounds of applause, even as many of them took cover in the two shade-tree areas on the edge of the stage. Temperatures already had hit 90 before Mandolin Orange finished, prompting the band to thank the hundred or so hardy fans who stood up front in the “horrendous direct sunlight,” as Frantz put it.

Among those in the crowd was a flag-bearer sporting the state colors of North Carolina, the duo’s home turf. Their pastoral folk tunes are rooted in Carolina country music, and when Marlin and Frantz combined their voices in harmony, they created magic that carried beyond any distractions of omnipresent ACL Fest heat and noise.

The band has played Austin at least a half-dozen times in the past two years, so it meant something when Marlin said that “Austin’s absolutely one of our favorite towns.” This was their first visit to ACL Fest, and it extended a good run for the small BMI Stage this year, with many quality performances by locals and nationals alike.