The Armenian brother-and-sister team give passionate, deeply felt performances of all three sonatas. Recorded in London’s Wigmore Hall, the sound is notably warm and enveloping. Sergey’s playing is highly polished. He eschews almost entirely the expressive portamento: this, and his unwillingness to pare down his rich, lustrous tone, gives his playing a less varied sound than, say, Renaud Capuçon’s. Similarly, Lusine concentrates on a finely balanced sonority, and there are places where a less liberal use of the sustaining pedal – in the third movement of Op 108, for example – would help to characterise the music more sharply.

As interpreters, the Khachatryans are more in the tradition of Egon Petri and Szigeti than that of Serkin and Busch; that is, they feel free to modify the tempo to accommodate changes in texture and mood (whereas Busch and Serkin generally confine themselves to what the composer indicated). Sometimes such modifications seem excessive – for instance in the tranquil parts of Op 100’s Allegro amabile – but they certainly allow projection of the music’s constant expressive changes. Curiously, I felt the più andante in Op 78’s Adagio might have been more marked: this part of the movement seems rather too heavy. But what gives these performances their particular strength is the performers’ ability to project the crucial movements of harmony on which the sense and appeal of Brahms’s music rests. Some tracks – the Adagio of Op 108, by turns serene, passionate and delicate, or the flexible, lyrical account of Op 78’s finale – have hardly been bettered.