There are other difficulties with the viola, an instrument that, in a 2011 TEDx talk, Stumm describes affectionately as "imperfect" and "the middle child" of the string section. One troublesome issue is a lack of repertoire from the likes of Beethoven, Bach and Mozart.
"The big time for the viola started in the 20th century," Stumm says. "There are some fantastic sonatas that span history but our repertoire doesn't go as deep as the violin and piano, in terms of pieces by 'canon' composers."
Although Britain is now home – she is international chair of viola studies at the Royal College of Music – Stumm is originally from Atlanta, Georgia. There, she was fortunate to come into the orbit of Marilyn Seelman, an inspirational viola teacher who, according to Stumm, has built a "little viola dynasty" in Atlanta, with several of her students going on to win competitions.
Stumm has always given lessons, too. As a school kid she taught strings to youngsters in Atlanta's tough inner city, helping to convince a local violin shop to donate instruments.
These days she is founder and music director of Illumina, a chamber music initiative centred round a festival that takes place annually in Sao Paulo, Brazil. Illumina's ambitions are as much social as they are musical, with the aim of helping marginalised people become professional musicians, while bringing some much-needed diversity to the top level of classical music.
"There's no reason a social initiative can't carry enormous musical quality," says Stumm. "All the young musicians come from lower socioeconomic backgrounds and would have no other way to advance their studies and make it to a large conservatory."
Illumina has a 100 per cent hit rate. Every one of its 60 musicians who have applied to study at a conservatory has been accepted, a source of both pride and concern: "The fundraising burden is very high".
Stumm says she gets her sense of social justice from her grandmother, a Cherokee Native American from Appalachia, and reckons that's where she gets her musical genes, too.
"She never really learnt to read music but she could play anything by ear. If my grandmother had musical training she could have gone to Curtis [Stumm's own alma mater], but she had a grade-school education. So to me, playing at the top levels of classical music is a wonderful thing, but not if I'm not extending the hand to make sure that everybody gets the chance to experience it."
Stumm is a tireless advocate for the viola, which explains why her NZ tour presents the instrument in a range of settings. There are works for viola with piano, an important chamber piece in the form of Brahms's lovely Piano Quartet No.3 - "viola at its most beautiful," she says - and solo pieces including three blink-and-miss-it selections from Gyorgy Kurtag's set of miniatures Signs, Games and Messages.
Stumm varies her Kurtag choices from concert to concert but many of the best are extremely delicate. How do you make that work in a concert hall?
"You always have to consider the venue but in general I love playing soft music. We live in a noisy world and in a big city like London, where I live, there is almost no silence. So to go to a concert where people are almost required to lean in and pay attention is rare but really important."
Lowdown
What: Jennifer Stumm with Te Kōkī Trio
Where & When: Six concerts nationwide, August 8-15. Auckland concert Thursday, August 15, Town Hall Concert Chamber. Chambermusic.co.nz for detail.
