The pairing of an innovative but sensitive guitarist with a singer who works and explores the voice is a bracing, all-too-rare format. Raül Refree perfected it with both Sílvia Pérez Cruz and Rosalía, to stunning effect. The Portuguese singer Beatriz Nunes and the guitarist André Silva, whom I saw Friday night at Drom, are of a comparable order: not mere singer and accompaniment, but a vivid, ironic dialogue. The guitar serves and follows the singer and also leads her. It is hard not to think of Hegel’s master-servant dialectic, but between equals, even if one, the guitarist, is in clear support of the other.

They sat, angled slightly toward each other, as though for an interview. As on any good talk show, interesting facts emerged. Nunes, to begin with, has voice of primal purity. I have enjoyed her work with the exceptional Portuguese folk band Madredeus (it is unclear if they are disbanded or simply dormant), but was unprepared for the depth of her personal art. She’s a vocal conduit for deeper things, drawn from the soil and the bigger universe; her wit, facial liveliness, and theatrical flair evoke chanson and cabaret; she gives grace to seriousness and hope to the tragic.

Her voice and repertory are a study in variety; she’s equally at home with tradition and the songs she writes. Trained in jazz, classical and folk, she disclaims herself as a fado singer, but she sang one on Friday, and there were hints of it in another. And in a guitarless solo, I caught something of the larger Mediterranean, of African and the Arabic. Whether it was influence, affinity, or an actual borrowing, I couldn’t tell: it was neither my language nor culture. But it wasn’t abstract sound, either; its emotion was bodily and it meant something.

Nunes is as real a singer as they come; technique without artifice, except as grounded in the lyrics (those wonderful expressions and hand gestures); her voice unblocked and natural as an unspoiled stream. She’s one of those artists who, when seen live, feel like discoveries, even if you’ve heard them online or CDs. It’s not that they are “better live”; it’s that presence is the essence of their art. They are the best artists if I had to choose, and she is one of them.

For more on Beatriz Nunes, click here. The guitarist Andrés Silva plays with The Rite of Trio. Click for information on programming by Arte Institute, which sponsored the performance. Visit Drom for upcoming events at that venue.