It’s perhaps an unusual choice to have the opening sounds of Bartók’s Second String Quartet, a little tender, a little recalcitrant, announce the start of this most impressive 20-day celebration of orchestras around Europe and the world. True, there are several important chamber concerts in the Musikfest Berlin schedule this year, which will cover the complete quartets of Bartók and Janáček, among other appetite-whetting offerings. But the vast bulk of the festival is dedicated to the great orchestras of today, giving one a nearly unparalleled chance to hear a dozen major international ensembles back-to-back, in the same hall.

The official start to the festival is tonight, Saturday, when the Pittsburgh Symphony Orchestra walks onstage at the Philharmonie. But first there is the Emerson String Quartet to talk about, which arrived in the smaller Kammermusiksaal on Friday with its newest addition: English cellist Paul Watkins, who earlier this year replaced the long-serving David Finckel. I remember listening to the Emerson box set of the complete Beethoven String Quartets throughout college, admiring the freshness and near-improvisatory inventiveness with which they handled the demanding architecture of some of the late quartets. When I heard Watkins last night, my enthusiasm for the group only increased: for here is the rare quartet cellist whose bass effects positively crackle with life, whose dedication to the expressiveness of every note polarizes the quartet’s sound from the bottom up.

For nearly a decade, Watkins was the principal cellist of the BBC Symphony Orchestra, and if I say that Watkins’ playing in a chamber setting retains his orchestral imagination, I hope it is understood to be a great compliment. When Mendelssohn’s Sixth String Quartet in F minor, Op. 80, begins with an agitated tremolo that mimics an operatic concitato, Watkins somehow manages to make his single instrument sound like a feverish band of cellos, scrabbling away furiously in the pit. He evokes the size and depth of a section’s sound while maintaining a precision of articulation obviously impossible in an actual ensemble – this may be something like what an orchestra is supposed to sound like, in a composer’s imagination.

The violinists Eugene Drucker and Philip Setzer have a wonderful understanding with each other, especially in fluid contrapuntal sections, creating long strands of continuous sound. This was, obviously, a requirement more of the Second and Sixth Bartók Quartets than of the Mendelssohn, though the Mendelssohn was the best-played piece on the program, both impeccable and enthusiastic. Something about the Bartók numbers gave me pause. I wonder if I was hoping for more lilt and dance in certain sections, and especially from the first violin, Philip Setzer. His playing was wonderfully colored, controlled, and textured, though perhaps a little reserved for my taste. The Bartók quartets can open up when given a little oxygen, that is to say, when played a little more from the inside, finding moments of expressiveness and pause as a way of balancing a focus on the pieces’ larger form.

This is serious music, but to always play it seriously can be a drag. Think, after all, of the gypsy-ish dance in the last quartet when the violist Lawrence Dutton grabbed his instrument like a banjo! The audience laughed – at the sight, probably, but perhaps also because they sensed they were hearing something different from these wonderful musicians, concentration tempered with joy. The rest of this quartet needed a little more of this flexibility, perhaps of this sincerity. Excessive strictness can limit its beauty.