From the very first notes they played at Sage Gateshead last night, I was struck by the incredible beauty of tone that the Borodin Quartet produces: somehow, the magnificent depth and richness of an entire Russian orchestral string section, is condensed into four players. What also quickly became clear was their absolute unity, with each player dedicating himself entirely to the collective sound as they glided and danced serenely through quartets by Borodin, Shostakovich and Beethoven. Whenever they played in the unison, the instruments blended perfectly into a single sound, and throughout the concert, they achieved their perfect unanimity with almost imperceptible gestures: a slight movement of a finger or an eyebrow, the merest glance at a colleague.

Borodin’s String Quartet no. 2 in D major was a good introduction to the quartet’s playing style, showcasing their gorgeous lyricism in the first and third movements and their delicate touch in the fast movements: at one point during the second movement, Igor Naidin’s bow barely seemed to touch the strings of his viola, yet the sound pinged out, pure and quiet. Cellist Vladimir Balshin and first violin Ruben Aharonian were unashamedly romantic as they sang out the famous theme in the third movement (Notturno), and the lyrical opening movement glowed with contentment. Borodin dedicated this quartet to his wife, and to judge solely by the music and the way the Borodin Quartet played it, it must have been a blissfully happy marriage.

The unvaryingly gorgeous, silky tone was a joy in the Borodin and in the Beethoven, but its unbroken perfection was too much when it came to Shostakovich’s Eighth String Quartet. This, the most famous of Shostakovich’s quartets is a piece full of ambiguity and multiple levels of meaning. It was written in Dresden and was dedicated to the “memory of victims of fascism and war”, but it is also loaded with autobiographical references: there are quotes from Shostakovich’s other works and his signature DSCH motif (D-E-flat-C-B) is never far away. Although at times the opening Largo was heavy with quiet menace, when it comes to the explosive Allegro that follows, I expect to be cowering in a corner in despair and terror, and this performance simply lacked that raw edge. The beautiful Largo that closes the quartet was weighted with grief, and was intensely rich and dark, the absence of pain earlier meant that there was less of a sense of healing and peace.

It’s sometimes hard to get immediately back into the mood of a concert after the interval, but for the opening of Beethoven’s last quartet, his Opus 131, the Borodin Quartet simply picked up the mood from the end of the Shostakovich, and continued in the same vein, as though we’d never been away. The first movement unrolled in a quiet but restless search that had me completely transfixed, and the variations of the fourth movement, held time suspended. The slow rising cello interjections that can sometimes sound like an interruption slotted in perfectly, and there was more wonderfully unanimous playing to enjoy. It’s hard to believe that this was one of Beethoven’s very last works, for this movement paints a picture of a man who thinks he still has all the time in the world.

There was more sunny charm on display in this lovely quartet too – the second movement a lightly poised dance and the frolicsome fifth movement flew, gossamer-light into the air; again the players’ bows just glancing off the strings. The final movement shifted seamlessly between Beethoven’s changes of tempo and temperament like a well-oiled machine; the Borodin Notturno showed the quartet’s romantic side but here, finally we had a glimpse of some real passion.

This passion continued into an encore that was, for me, the unexpected highlight of the evening. As the players settled themselves back at their stands, my heart sank, briefly – I’m not a big fan of encores anyway, and I know Russian musicians have a habit of over-indulging in them, but Shostakovich’s Elegy for String Quartet, based on an aria from Lady Macbeth was an absolute delight, a wistful, haunting violin solo over a restless accompaniment and a perfect way to round off the concert.