After a week of big orchestras and big works, Musikfest Berlin took a breath by returning to the Kammermusiksaal at the midway mark of the festival. Quatuor Diotima, a French ensemble that’s known for playing a lot of new music, on this night offered us the two Janáček String Quartets and Bartók’s Third and Fourth Quartets; the Philharmonia Quartett Berlin will finish off the last two Bartók Quartets on Sunday.

Bartók’s Third and Fourth Quartets were written one after the other, in 1926 and 1927, but while they share a stylistic palette, the Third is tightly wound while the Fourth allows its moods to expand into whole regions, recalling the construction of the late Beethoven quartets. Some of the moods, or regions, are in fact similar: arioso or recitativo sections, fast motivic romps, dances, dense and highly varied contrapuntal movements. What we do not find in Beethoven is the sheer kineticism of some of Bartók’s gestures – some moments seem to be built on physical choreography rather than notes.

The Fourth Quartet sports an arch form across five movements, with the even-numbered movements providing scherzando relief – the fourth is played all pizzicato, a marvelous invention. But Bartók was not the only composer writing in Beethoven’s shadow this night: Janáček’s First Quartet is subtitled “Kreutzersonate”, and the Second (on which the violist was replaced by Garth Knox on viola d’amore), subtitled “Intimate Letters”, reminds me somewhat of the structure of Beethoven’s Op. 130 in its revised form, after Beethoven took out the Grosse Fuge that was supposed to end it and replaced it with a country dance, suffering a moment of obedience or uncertainty. The Janáček quartet, too, moves through three rather complex and expressively undecided movements before the last movement brushes away the cobwebs in a sturdy romp.

It could have been that the works on the first half, the Third Quartet of Bartók and Janáček’s Second, were fresher, or that the ensemble needed time to find their groove, but the second half improved noticeably, with the quartet’s confidence and precision in ensemble playing reaching a real solidity. For them, ornaments such as the trills that overrun the last movement of Janáček’s “Kreutzer Sonata” do not shy away from disturbing the core of the note, but become rogue elements in themselves, showering the hall with vibrancy. I admired, too, the way the cascading harmonies at the beginning of the Adagio from Janáček’s Second Quartet shimmered so wonderfully. Quatuor Diotima is a group that plays with big colors, a feature that makes them well worth listening to in spite of the occasional lapse in finesse.