It was a night of broken strings and musical intensity for the Tokyo String Quartet as they played their 45th recital for Music Toronto at the Jane Mallett Theatre.

Although they have two more concerts scheduled for Music Toronto later this season, it was impossible to ignore the emotional elephant in the room: This storied chamber ensemble is saying goodbye forever this coming June, after a remarkable, 43-year run.

Not only has Toronto enjoyed a special place in their intensive touring schedule, the city has a deeper connection through former first violinist Peter Oundjian, the current music director of the Toronto Symphony. And their current first violin, Martin Beaver, spent several years teaching at the Royal Conservatory before joining the quartet in 2002.

But the real reason to mourn the impending end of the Tokyo is the quality of its musicmaking. Violinists Martin Beaver and Kikuei Ikeda, violist Kazuhide Isomura (a founding member of the quartet) and cellist Clive Greensmith bring an exceptional level of finesse to what they perform.

Their final season includes the completion of a complete cycle of the six string quartets by Béla Bartók.

These men are not exactly taking the easy way out as they extend a protracted goodbye. The Bartók quartets require tremendous technique as well as great subtlety on the part of the performers.

And, on the part of the audience, they demand a leap of faith that all of the dissonances and bumper-car rhythms will be worth the intense concentration they require.

The Tokyo delivered in Bartók’s String Quartet No. 4, from 1928, and No. 5 (1934), which opened the evening. The intensity of both quartets was unintentionally underlined by snapped violin strings.

Beaver lost one less than 3 minutes into the Fifth Quartet; one of Ikeda’s violin strings broke near the end of the first movement of the Fourth, after intermission.

Some musicians think that, because of the jagged rhythms and short, bullet-like musical patterns, a lot of Bartók’s music has to be played with the finesse of a machine gun. But, as the Toyko showed, there are nearly infinite dynamic shades to add interest to the music.

The most magical experience of the evening came in the slow second movement of Quartet No. 5, which contained an extraordinary juxtaposition of intensity and calm, stasis and movement.

The four men were in such control of their material that they were able to bring a degree of polish and subtlety to all of the music that one doesn’t always to hear in atonal compositions.

The sweet-cream filling in the evening’s Bartók cookie was Joseph Haydn’s “Rider” String Quartet, Op. 74, No. 3, which dates from 1793.

It was a fascinating choice for this programme, as it showed a similar devotion to structure and symmetry as well as dance forms on the part of the composer — but rendered in a much older, tonal language.

The Tokyo Quartet returns to Music Toronto on April 4 to complete the Bartók cycle with Nos. 3 and 6 and to perform a farewell benefit concert the next night. Either or both are well worth experiencing.