The Emerson String Quartet (above) has been playing together for - well, actually for only thirty-three years, but considering the group has never suffered a single change in personnel*, it probably counts as the Methuselah of string quartets (particularly when other venerable musical partnerships, like the Beaux Arts Trio, have been taking their final bows). Its violinists, Eugene Drucker and Philip Setzer, both studied under the same teacher (violinist Oscar Shumsky), so their connection goes back even further. When the Emersons (who named themselves after the great Ralph Waldo) begin to play, you sense immediately that everything that needed to be worked out between them was settled long ago. Long ago. As in eight Grammys ago (the number the quartet has been awarded - soon, perhaps, to be nine, as their current album, Intimate Letters, has been nominated).

And for their Celebrity Series concert last weekend at Jordan Hall, the Quartet dipped into the well of music they know extraordinarily well - the Ives Quartet No. 1, "From the Salvation Army," (for which they won a Grammy in 1993), the Shostakovich Quartet No. 9 (another Grammy win in 2000), and Janáček's Quartet No. 1, "The Kreutzer Sonata" (currently nominated). They also threw in the original quartet setting of Barber's Adagio for Strings as a crowd pleaser, I suppose.

These were clearly performances - and interpretations - long set in stone, but none sounded rigid, or in any way dusty. After better than three decades, the Emersons are still engaged, with both the music and each other - still, they don't exactly do passionate battle onstage (even though only cellist David Finckel remains seated; the rest stand). And frankly, they don't do irony, either: the opening Ives quartet, "From the Salvation Army," sounded almost as earnest as Copland, even though it takes its source material (several popular hymns - the piece is subtitled "A Revival Service") and deconstructs them with blithely cool arrogance. The quartet played the piece flawlessly, but frankly there's a sense of journey here - a voyage from familiar harmonic uplift into some larger, colder musical space - that the Emersons simply didn't seem inclined to take.

They were far more convincing in the Janáček, which is structured like a kind of opera, with leitmotifs that criss and cross each other in a steady build into tragedy (it's modeled on Tolstoy's classic account of jealousy, "The Kreutzer Sonata," itself inspired by the Beethoven piece). This was great music-making, and great drama - although Janáček hardly matches the moral complexity of the original novella. Tolstoy's POV is the jealous husband's, who is eventually acquitted of the murder he commits (but is nevertheless obsessed with forgiveness); Janáček's is the brutalized victim's, led astray by the sinuous themes of her seducer - a violinist, appropriately enough for a string quartet - and pursued relentlessly by a clutching, scratching, nearly demonic voice. The Emersons kept the intensity of the later movements rising, inexorably, even in the andante sections, so that the final blows, and eventual regret of the murderer, were devastating.

What followed - after lead violinist Drucker traded places with Setzer (another Emerson tradition) was a lovely, but inherently anticlimactic, rendering of the Barber Adagio. It seemed an odd choice at this juncture in the program, but as it's one of the most luminous stretches of melody ever composed, I confess I'm always happy to hear it.

The quartet's intensity returned (and then some) with their final offering, Shostakovich's String Quartet No. 9. Here everything seemed to fall into place, from the mournful phrases of the opening Adagio to the menacing cackles and dancing chases, flecked with both the comic and macabre, of the later movements. Indeed, the Emersons threw themselves into the work's nearly-infernal frenzy with such force that violist Lawrence Dutton broke a string with one violent pizzicato (the frenzy resumed after a moment's pause for repairs). This was merely the outer sign of a thrillingly fierce performance that brought the audience to its feet. The group returned for a single encore, a lovely setting of a Dvořák song. After the fury of the Shostakovich, its gentle lyricism was most welcome.

[*Note: I've been informed that the Emerson at its inception briefly played with a different cellist and violist, so the current line-up is only thirty, not thirty-three, years old. Point taken!]