One string quartet turned in an exquisitely detailed performance of Mozart's Hunt quartet. Another steered a course back and forth between ardent and fiery in Brahms. Still another foursome processed Kurtag's rigor with an exactitude almost frighteningly machinelike.

It was, of course, the same quartet performing all three works Wednesday night in the Kimmel's Perelman. The Elias String Quartet has become one of the highlights in the Philadelphia Chamber Music Society's quartet series, and the depth of their stylistic malleability created the illusion of three different groups. And this wasn't even the most impressive thing about the London-based ensemble.

What has emerged from this fourth visit is how every single note has been thought about and phrase chiseled to realize a piece's true character. When first violinist Sara Bitlloch opened the Mozart, the quartet K. 458 in B Flat Major, she gave those descending triplets not a clarion hunting call, but a sound more relaxed and nuanced. Every idea, even the slightly perturbed development section, followed the same philosophy of sound. Players all maintained a noble mien, but gave each phrase a life elaborately shaped. Individualism within bounds.

The third and fourth movements were ensemble playing on a sophisticated level. About the unison rhythms that ended the third movement: the perfection of unanimity with which the Elias hit those grace notes doesn't generally happen in the mortal world. The subtle accommodations they made to each other in the fourth with pacing, balance, and dynamics suggested a single expressive organism.

Steely, terse, nocturnal, halting, nervously coiled, spooky and a continuous stream of non sequiturs. No one avoids the obvious contours of music — the ones we've been conditioned to listen for — the way Kurtág does. Which is both a very good reason to be grateful that the Elias played his Six Moments Musicaux (2005) and yet another reason to be awed by the ensemble. Kurtág offers up and claws back each emotion in a flash, which means players must be instantaneously convincing. They were. Finding meaning in it is a personal challenge for some listeners, but if a game, the Elias was a master. Most jaw-dropping feat: a texture so distantly quiet that you knew cellist Marie Bitlloch would never be able to come in with equal delicacy. And yet she did.

Pianist Jonathan Biss playing with the Elias String Quartet at the Perelman Theater on Wednesday night.
Pete Checchia
Pianist Jonathan Biss playing with the Elias String Quartet at the Perelman Theater on Wednesday night.

The Elias didn't quite strike the same points of evolved interpretive thinking in the Brahms as in the other two works, though it didn't matter much. The piece brought with it pianist Jonathan Biss, with his usual frisson as a bonus. In the Piano Quintet in F Minor, Biss and cellist Bitlloch blended sounds beautifully, and the way he dovetailed with the group — especially in the fourth movement — was a source of constant pleasure.

Here in Brahms, the group took more liberties than elsewhere, with violist Simone van der Giessen flashing a brighter sound (she is substituting for Martin Saving) amid the shifting colors of the first movement. Their ensemble precision snapped into place at critical points. Chief among them was in the marchlike third movement when, after a sliver of silence, they showed that sudden unanimity can make for a sound explosion of the happiest kind.