On Bachdag Amsterdam, a day of concerts devoted to celebrating the music of Johann Sebastian Bach, viola da gamba and harpsichord duo Lucile Boulanger and Arnaud de Pasquale performed works by Bach’s 17th-century German predecessors, culminating in works by Bach himself. Two of the works were anonymous sonatas from the late 17th century. One of these, a complex, virtuosic sonata in the stylus phantasticus, came from a Lübeck manuscript now in the Bodleian Library which also contains music by important composers such as Dietrich Buxtehude. This impressive piece opened the concert, and immediately offered an opportunity for Boulanger to shine, with her silky legato and very delicate passagework.

The two performers had a delightful musical chemistry onstage, de Pasquale supporting the delicacy of Boulanger’s playing with imagination and warmth. De Pasquale’s interpretations were sensitively judged, but the harpsichord itself sometimes threatened to overpower Boulanger’s thread-fine pianissimo. With skilful balancing on both sides, Boulanger managed to blend smoothly in and out of the sound of the more powerful instrument. The duo’s interpretation of August Kühnel’s Sonate VIII and Arie Variate was delightful, accomplished with great agility and a joyous, dancing sense of fun. Bach’s Sonata in G, BWV1027 and his Sonata in E minor for violin and basso continuo, BWV 1023, here transcribed in D minor for viola da gamba, showcased the duo’s gifts beautifully. The slow movements of both works particularly stood out, accomplished with languid, melting phrasing from Boulanger, underpinned by de Pasquale’s dreamy, rocking accompaniment.

Arnaud de Pasquale seemed to feel some tension in Bach’s Toccata in D, BWV 912, much of which he took at a daringly fast tempo. There was definitely an element of discomfort here, with a few audible slip-ups, although he maintained energy and commitment throughout. It’s probably not what he would prefer to hear, but the recovery of happiness in his face when the audience showed their appreciation at the end of the concert with a standing ovation, was awfully endearing. Sometimes it’s rather inspiring to hear things go a little bit wrong in performance, especially for an obviously gifted player – it reminds one of just how impressive and exciting the balancing act between preparation and spontaneity on stage really is. De Pasquale’s solo Prelude in G minor by Dietrich Buxtehude, BuxWV 163, showed his true capabilities. He brought a rich sensibility and a liquid, reverberating, harp-like quality from the instrument through well-judged sustaining of notes.

It is actually fascinating when one gets to see a hint of the performers’ journey onstage: the chemistry that comes from the musicians’ relationships with the music, each other and the act of performing itself. This is why an intimate chamber concert with only a small number of musicians can be so powerful and rich. I felt a little unsettledness in Lucile Boulanger’s playing at the very beginning, evident more as a feeling than as an identifiable feature of her playing, but she swiftly settled to a calm that became deeper and more intense throughout the concert. This change did show in her approach to high notes – at the start there were some very slight misjudgements in the high notes, which towards the end she was correcting with apparently effortless poise. By the end of the concert, I felt I was witnessing something like a Zen practitioner in meditation, so deep was the underlying serenity of her playing and her presence. Her one solo piece, Johannes Schenk’s Sonata VI from L’Écho du Danube, showed the strong foundations of her craftsmanship. She explored the contrasts of the piece with relish, giving a severe and stately grace to the adagios and committing boldly to the toe-tapping, folk-like character of the concluding Giga.

Boulanger’s playing has a distinctly rare and personal quality, a silky, creamy legato that underpins all her playing, including fast or detached passages. Her slow and cantabile passages are breathtaking, accomplished with outstanding delicacy. It is as though she were playing on a single, constant breath. This allows for exceptional refinement of phrasing and a sense of conceptual and interpretative unity to which the audience has to respond. An artistry in which sophistication and honesty are so firmly united cannot help but touch the heart.