It’s difficult to explain what makes the Danish String Quartet’s playing so special. Other ensembles arguably match these players in technical excellence and interpretive insight. To say that their performances represent a marvelous balancing of qualities suggests that they occupy some place in the middle of the road. The results are anything but: There is a winning mix of studied concentration and willful freedom in their playing. “All Scandinavians feel like they have a bit of an anarchist inside them,” Asbjorn Norgaard, the group’s violist, said in a 2016 interview. That came through during this entire series.
Their technical command resulted in precise execution. Yet they played with enough leeway to allow instinctive responses to take over in the moment. You might assume that musicians in their 30s would bring youthful energy to bear, but I was struck by how often they opted for a raptly restrained tempo. Rhythms were dispatched with clarity and exactitude, without a trace of rigidity.
They have a shared sensibility and richly blended sound. But that doesn’t stop their individual musical characters from continuously shining through. (The members, besides Mr. Norgaard, are Frederik Oland and Rune Tonsgaard Sorensen, who trade playing first and second violin parts, and Fredrik Schoyen Sjolin, a Norwegian cellist who has been with the ensemble since 2008.)
The big endurance test of the cycle was the third program, in which they played the three “Razumovsky” Quartets (Op. 59), from 1806. Here is the towering Beethoven, the composer as revolutionary, striding across the pages of these scores — brash, adventurous and ingenious. I found the performance here of the middle one, in E minor, especially distinguished. The Danish quartet brought out both the brooding weightiness and near-crazed intensity of the music. The ebullient third, in C, ends with a quasi-fugue finale, a breathlessly fast tour de force with streams of rapid-fire notes. For an encore, they repeated the final large section of that movement. And, with nothing to prove, they played with an extra dose of daring.
It’s hard to single out movements, or even moments, from the ensemble’s accounts of the late quartets. I loved how they began the Quartet No. 12 in E-flat (Op. 127), which opens with what seems a fanfare, in thick chords, that soon spins off into a genial exploration of a winding theme. The Danish quartet underlined this passage with grit and urgency that sent a signal: A gate to a new path had been opened.