And Merlin has noticed cultural differences in the way audiences react to the music.
"People are more connected to certain elements. Japanese people are very respectful of the silence around the music. Brazilians are more connected to the rhythm and harmony, which is part of their culture of bossa nova or traditional Brazilian music."
The quartet is not at the end of its ethnographic observations. The tour, which began in Katonah, New York State in April, doesn't finish until the musicians return home to Paris in January 2020. They get a few weeks off before flitting to the US for the Carnegie Hall shows. So much travelling is involved that the group is starting an environmental programme in partnership with Air France to offset carbon emissions.
It must be difficult to remain focused. Not so, says Merlin.
"Touring is very tough, but you keep active and fresh by the travel and being in different places; it's easier to stay focused than if we'd been recording in the studio, because we have the inspiration of an audience."
What has Merlin learnt about Beethoven that he didn't know before?
"I understand better now how disturbing Beethoven was in his time, and that he's still disturbing us. This is not background music; it asks deeper questions."
Such as?
"There is something ambitious in Beethoven's music and if you don't come to terms with that dimension then your playing will be of a lower standard. Compare Beethoven to Schubert, the other great figure of the same period. Schubert was saying 'i' with a small letter, with intimacy, expressing what happens in his own mind and soul.
"Beethoven spoke with a big 'I', addressing the whole of humanity and future generations. His music is no less modern now than it was in his own time. In only 30 years of activity his music evolved as much as the musical evolution between Haydn and Bartok. The trio in the scherzo from Op.135, if you listened blindly you'd probably classify it as American minimalism. We knew that but now we feel it organically."
What have the musicians learnt about each other? Mostly, Merlin says, the group has come to better understand violist Marie Chilemme, who joined the Ébènes in 2017, when planning for the Beethoven Around the World project was already in full swing.
"You cannot guess the nature of someone before spending a few months or years on tour. She had to get to know the way we work, we had to change a few things, but there were great benefits in terms of harmony and coherence."
It's hard to tell how the personnel change has affected the Ébène sound. The group has always been rhythmically sharp but perhaps there's an extra earthiness, now. The quartet can and does play beautifully, but the musicians aren't afraid to play ugly, either. It's one of the best things about them.
"To reach the real meaning of Beethoven's music, you should not play with too much respect," Merlin says. "Someone said don't play with respect, play with love. If you play music only with respect you can betray it; if you play what you really feel, then you become an interpreter of it."
Lowdown
What: Quatuor Ébène – Beethoven Around the World.
Where and When: Michael Fowler Centre, October 25; Auckland Town Hall, October 26
See chambermusic.co.nz
