It was admired for its rich, warm, complex tone and its bold, dramatic interpretations of the quartet literature, with a particular affinity for the works of Beethoven and Bartók.
The group's extensive touring and recording activities, coupled with its outreach efforts to engage audiences, contributed to the rapid growth in the popularity of chamber music during the 1970s and 1980s.
The quartet is notable for its longevity: the group performed for 45 years with only one personnel change, when cellist David Soyer retired in 2001 and was replaced by his student Peter Wiley.
In the quartet's early years Tree played a viola (patterned after Andrea Guarneri's "Conte Vitale") made by Harvey Fairbanks, a luthier from Binghamton, New York.
Steinardt relates that the group found the situation attractive because Binghamton was within driving distance of their base in New York City, and it would provide an opportunity to rapidly build a repertoire, gain performing experience, and develop working relationships among themselves.
[23] The Guarneri's New York City debut took place on 28 February 1965 at the New School for Social Research as part of a concert series arranged by Alexander Schneider.
In the summer of that year they embarked upon their first European tour, performing in Geneva, Basel, Amsterdam, Cologne, and at the Festival of Two Worlds in Spoleto, Italy.
The affiliation with Harpur College continued until 1968, and in that year Steinhardt, Tree and Soyer were appointed to the faculty of the Curtis Institute of Music in Philadelphia.
"[19] Critics agreed that it was time to bow out; while still praising the Guarneri's tone and style, they perceived increasing technical imperfections and a decrease in the intensity of the group's emotional connection with the music.
It has been described as "suave, elegant, highly nuanced, technically flawless",[37] as "lush and vibrant sound married to an intensity of purpose",[35] and as "seamless, warm and impassioned playing [with] a unanimity that did not efface individual personalities.
"[25] Philadelphia critic Daniel Patrick Stearns remarked that: Audiences kept coming back for the warmth of tone that was built from the inside out, with an unusually strong presence from second violin and viola, but with soft attacks and releases.
"[38] In another context he stated that "our top priority is to try and deliver the essence of the music and create goosebumps – give a performance that will be as memorable and vital and energetic as possible.
[35] Many quartets strive to present a clean and cohesive tone, working to coordinate phrasing, bowing and intonation so as to create the sense of a single instrument with four registers.
David Blum notes that the Guarneri explicitly followed a different path: They readily admit that other quartets look for and achieve a more consistent blend of timbre and unity of style.
[29][44] The group also made a point of performing seldom-heard quartets by earlier composers, including those of Jean Sibelius, Leoš Janáček, Zoltán Kodály, and Juan Crisóstomo de Arriaga.
[45] Unlike most performing ensembles, the Guarneri permitted, and even encouraged, public awareness of their work as they prepared concerts, and they allowed backstage glimpses of the interpersonal dynamics within the group.
[G] The group insisted that all of the players were equals, and as a symbol of this, determined that whenever a piece called for one violin (for example, a piano quartet), second violinist John Dalley would play that part unless he chose not to do so.
[48] Similarly, all decisions were to be made by the group as a whole – and since four is an even number, that stance guaranteed a great deal of discussion when two members favored one option and two others preferred a different one.
[50] In general majority opinions prevailed, but a minority voice was listened to, and occasionally when one member had extremely strong feelings on a matter, he was allowed veto power.
But praise was almost never expressed; Steinhardt describes the Guarneri as a "compliment-free zone," noting that this reduced competitiveness and eliminated any pressure to offer congratulations in return.
[57] The devices the players used to resolve problems and maintain their personal privacy, combined with their genuine fondness for each other and for the music they played, made possible an unusually long life for the quartet.
The four original musicians performed together for 37 consecutive years, "a remarkable record of longevity for a string quartet, in which tensions over music making, money and personal differences often cause breakups.
[J] The quartet's longevity, along with the readily-available material about the group's interpersonal dynamics, has made it possible for the Guarneri to be used as a model in studies and pedagogy regarding collaborative leadership.
[16] The group's teaching at Harpur, at University of Maryland, and particularly at Marlboro and Curtis certainly helped young musicians to develop an appetite for quartet music.
[16] The four Guarneri players took a substantial financial risk by establishing themselves as a professional string quartet in the absence of bookings, recording contracts, concert management, or even certainty of sufficient public interest.
Their eagerness to communicate with their audiences, their interviews, open rehearsals, question-and-answer sessions all helped to make string quartets less esoteric, more familiar to listeners.