Twice during their performance, Micaela Vita told the audience how emotional it was for her and Willy González to be playing in Charleston.

It was the Argentinian duo’s very first show in the United States, a journey that almost didn’t come to fruition, after González, a bassist, experienced unexpected trouble getting through customs. If they follow up their stunning Spoleto performance with a North American tour, they’ll be hard-pressed to find a venue that rivals the ambiance of the Cistern.

Although clouds moved slowly over the live oak trees, the air at ground-level was balmy and still — fitting conditions considering that tangos and sambas are supposed to make you sweat.

When González and Vita took the stage just after 9 p.m., the bassist immediately established an ethereal mood by drawing sounds from his instrument through percussive taps along the hollow, wooden body. With his six-string acoustic bass broken in — it’s a giant beast of an instrument — González commenced with his equally percussive fret play. Vita wasted no time joining him, moving about the stage with sultry, expressive body motions that matched each stanza of her singing.

The duo’s set-up is simple. González switched between an acoustic and electric six-string bass, while Vita varied between the bombo legüero and cajón peruano drums. Vita is a true musician’s vocalist, using her body to raise and diminish the emotional response during a particular song. Although her microphone might have benefited from a touch more reverb at times, her control from three inches to a foot away from the mic was superb. However, when singing directly into it for entire verses, her voice occasionally cut dryly above the mix. Meanwhile, González’s mastery of the bass created a sense of constant improvisation, despite his flawless echoing of Vita’s vocal lines and each song’s intricate, synchronized changes.

This is, in fact, jazz. Although the rhythms the pair plays find their roots in sambas and tangos, these interpretations stretch traditional boundaries. If González found a groove, he was likely only to hold it for 30 seconds or less before moving on to the next bit of mind-boggling neck work.

Vita pointed out several times that their Argentinian style draws its roots from Peru, including her cajón, or box drum. In their third tune, a child’s song described as “a love story between two bugs,” González demonstrated an uncanny ability to simultaneously play intricate bass parts while blowing a pan flute melody.

One song drew from the hybrid Afro-Peruvian style, while others invoked festival moods in the tradition of Carnival. Vita drew hearty (unintentional) laughs when she explained that one song was about “a man’s relationship with his instrument,” then specified, “musical instrument.” The song included lyrics about the Peruvian stringed-instrument, the charango, accompanied by “coca con chicha” (coca leaves and homemade corn beer).

Many of the pair’s songs drew from folklore traditions, from “el campo” (the country) of Argentina and Peru. Love and relationships were a constant theme, including the set-closing “El Avenido,” about a man at Carnival who, in attempting to get himself alone with the girl he’s courting, offers wine to her watchful aunt.

Willy González is quite arguably among the world’s greats on the bass. He attacks the instrument like both a classical guitar and a drum, not afraid to use the deepest low notes of his bottom string. Micaela Vita matches his creativity, slinking across the stage and finding just-the-right syncopation for vocal lines amidst González’s frantic notations.

If you put González in a blues band with a 1-4-5 progression, chances are the song would quickly change time signature and key. He’s not a traditional bass player, but his mastery of the instrument and creation of a unique style is sure to inspire any bassist who hears him, from a stand-up jazz guy to a driving rock ‘n’ roller.

Sitting amidst the surreal atmosphere of the Cistern on a Friday night, it felt like something historic was happening. González and Vita didn’t draw the crowd that other Cistern shows can; in fact, chairs extended only halfway to the back of the courtyard. But those lucky enough to be present (and a few peeking through the gates) bore witness to an offering of pure emotion and musical energy that crosses language barriers. Even the trees leaning over the stage seemed conscious of the music’s power and appeared grateful to be hearing it.