Grammy-Award winning guitarist Sharon Isbin may have earned her outsized reputation, in part because she slips so easily between two distinct musical realms—that of soloist and that of collaborator. She gracefully wore both hats during her recent appearance with the Pacifica Quartet on BIG ARTS’s “Cool Classical” series, January 10 at Schein Hall.

Isbin and Pacifica have worked together for two years. She calls their collaboration “one of the best in the world,” and her description of their musicianship is effusive. “They are amazing human beings and extraordinary musicians,” she said. “They have such depth of passion and expressivity. They are creative and dedicated, and exciting as artists.”

Their program, which Isbin describes as “visceral and rich in harmonic content,” combined in equal measure music by Spanish and Italian composers. Two of the concert’s offerings are idiomatically Spanish, but written by the Italians Mario Castelnuovo-Tedesco and Luigi Boccherini.

Castelnuovo-Tedesco’s Guitar Quintet, Op. 143, provided the most musical muscle of the evening. Isbin views it as “edge-of-the-seat challenging, with extreme virtuosity required of all the players.”

The piece acts as a concerto, but with soloistic playing expected in all parts, not just the guitar. In this performance, Isbin’s deft sensitivity to collaboration was clear and present. She ceded prominence to the other players as each emerged one by one from dense contrapuntal textures.

Despite the piece’s heavy technical demands, the playing was unrestrained. Exquisite sonorities reverberated into the hall, bringing out the resonance of all instruments, including the sweet sounds of the guitar. The players frolicked, tossing gestures willy nilly from one instrument to the other. They gloried in their own musical audacity.

Pacifica entered into another type of concerto style with Vivaldi’s well-known Lute Concerto in D, transcribed for guitar and string trio. Performing more traditionally, the trio served in this case as support system for Isbin’s solos.

Isbin’s playing was authentically Baroque, subtly dramatic, but also patrician. Her effortless technique liberated her expressive impulses. She accentuated the most minute gestures with pristine clarity, her fingers gliding friction-free along the fingerboard.

The slow, second movement was particularly effecting, its meditative qualities sustained by the purity of Isbin’s tone and the beauty of the gentle, improvised embellishments that she added to the theme. The Pacifica players maintained a steady pulse beneath, cushioning Isbin’s lyrical ruminations. The result was mesmerizing.

Isbin calls the Boccherini Quintet “a beautiful experience for the guitar.” Her lavish collaboration with Pacifica put that beauty on vivid display, the guitar’s rustic color qualities adding value to the whole.

The players obviously loved the piece’s concluding Fandango movement. Its relentlessly repetitive harmonic ostinato and its forceful rhythms kept listeners in thrall for the duration. It ended with a forceful, but surprisingly abrupt cadence that brought Isbin’s audience to its feet in heartfelt appreciation.

Upcoming this month and next on BIG ARTS’s “Cool Classical” series are renowned pianist Jonathon Biss, the Dover Quartet with pianist Peter Serkin, guitarist Alfredo Muro with cellist Natasha Farny, and the Parker Quartet. For tickets and scheduling information, contact BIG ARTS at 239 395 0900 or go to www.bigarts.org/performing-arts.