Harlem Quartet evinced a larger-than-life silhouette of Mozart as it played its final concert as the resident ensemble in NEC’s Professional String Quartet Training Program. Thursday evening’s small audience at Jordan Hall attentively kept an ear on Harlem Quartet. Schubert’s “Death and the Maiden” was sometimes under-monitored. In faintly mottled attire,the youngish foursome injected color and movement in an American mix of soundings from a recent work of American composer Judith Lang Zaimont. An encore ended the free concert on a fun and fittingly emblematic note, “Take the A Train,” inspired by The Duke instructing his future “alter ego” Billy Strayhorn on how to make his way to Harlem for their very first encounter.

Each of the members of the Harlem Quartet (not String Quartet, therefore allowing the rhyming Har and Quar) has studied with eminent teachers, apprenticed with internationally renowned artists, garnered prestigious prizes, even soloed with major orchestras. It has performed at the White House. But you might not ever have guessed before hearing these enormously well-coached instrumentalists that they would emerge as one single, unanimous voice, a spirited harmoniousness further crediting Gestalt theory in which the whole exceeds the sum of its parts.

First violinist Ilmar Gavilán, second violinist Melissa White, violist Juan Miguel Hernandez, and cellist Paul Wiancko, a newcomer, spectacularly made visible the many faces of Mozart cast in String Quartet No. 15 in D-minor, K. 421. My former colleague at the University of Massachusetts Boston, Professor Emeritus Robert Spaethling, an expert on the epistolary world of Mozart, concluded (as have many other scholars after their own extensive investigations) that the best way to get know Mozart is through his music – listening to it.

That is exactly and most exactingly the outcome of Harlem Quartet’s performance. Harlem turned phrases into faces, this one smiling, that one brooding, another not conceding, others surprising, tempting, yielding. The highly technically proficient quartet unanimously character-altered the deceptively simple black-and-white notes on the page from the opening minor sounds to the closing major sounds on the home key of D. No daydreaming allowed – needed – for the 30-minute stretch.

Judith Zaimont’s String Quartet “The Figure” (2007) gesticulated in a make-believe continuum, observably exciting the Harlem players, less so this listener. Potential existed in any given moment or texture of the two-movement work lasting 18 minutes. Some textures resting on deeper and quieter sustained yet dissonantly conceived harmonies were timbered in rich sylvan hues by Harlem. Ravel-like, maybe Debussy-like pastoral references, though, occupied adjacent scenes, creating questionable relationships that eluded me.

Schubert’s testament to dying, his String Quartet No. 14 in D-minor “Death and the Maiden” D. 810, took up the second half of the program. That this concert followed a programming plan of two such pieces, with the bigger or heavier one saved for last, has become a warhorse, a standard too often resorted to, and a reason why the quartet’s interpretation of this extended super-work did not faze until the return of the A section in the Scherzo, the third movement.

It could be possible, though, that the length of each of the first two movements – never mind their interior spaces – became a bit too much of a challenge. Impressive orchestral decibel levels and their opposites, while mustering sufficient contrast, did not occur naturally, this more in the variations of the Andante movement. The unrelenting drive that Harlem exacted of the Allegro was too much.

“Take the A Train” was pure delight. Away with the music stands, enter basso continuo on the cello, I mean swinging bass. Each took improvisatory turns. Takeaways: Harlem’s Mozart and Ellington-Strayhorn.

David Patterson, Professor of Music and former Chairman of the Performing Arts Department at UMass Boston, was recipient of a Fulbright Scholar Award and the Chancellor’s Distinction in Teaching Award. He studied with Nadia Boulanger and Olivier Messiaen in Paris and holds a PhD from Harvard University.