OK, almost always: the axing of an entire concert after a power failure at the Usher Hall last week probably counts as an exception to the rule. But of the two forewarned cancellations on the International Festival's recital platform, both have given rise to revelatory alternatives. The first was German mezzo Waltraud Meier, who filled Deborah Voigt's shoes with a beautiful Lieder programme on the opening weekend. Then when Welsh soprano Rebecca Evans withdrew from this week's Queen's Hall gig, the festival found another German operatic talent who is well appreciated at home but little known in the UK. Yet. Thirty-two-year-old soprano Christiane Karg makes her International Festival debut today, and has the potential to make something of an impression.
Karg is a product of Germany's enviable regional opera culture. Born and raised in small-town Bavaria, she spent her childhood accompanying her opera-loving father to seasons at Bayreuth, Bayerische Staatsoper and Oper Stuttgart.
"My sisters would fall asleep but I'd be on the edge of my seat," she tells me over the phone, her speaking voice every bit as sparky as her singing. "Our family wasn't particularly musical but our house is part of an old monastery and from a young age I went next door to sing in the choir. When I applied to university I didn't even know if I'd be accepted. I was appreciated in my home town, but I had no idea how I would compare in the wider world."
It turned out she compared pretty well. She studied at the Mozarteum in Salzburg, made her Salzburg Festival debut in 2006 and was declared Opernwelt's Singer of the Year – one of Germany's most prestigious operatic accolades – in 2009.
Rather than charging headlong into an international career, for the past five years she has been a signed-up ensemble member at Frankfurt Opera. This is a system we don't really have in the UK whereby singers are salaried to take several roles each season – something akin to company actors at a repertory theatre.
"Being in the ensemble is a really good place to start," she explains. "It's great training for the voice and allows us to learn a huge amount of repertoire. And because there are plenty of revivals we're not always singing under the glare of the press, so it gives room to experiment and grow."
Karg seems a fantastically grounded lass. She's chatting to me with sopping wet hair (she's just out of the swimming pool) and says she does some kind of sport for about an hour every day. "I'm always outside – in the summer there's no better place to be."
At the moment her home is in Frankfurt, and although her contract there is soon up she's in no hurry to rush off. "I don't want to think too much about the future just now," she says. "I've got no time to move apartments, and anyway I don't know where I want to move to." She'll be spending the next few summers singing at Glyndebourne. Then she says she might move to Paris to learn French, or maybe to Prague to learn Czech. "My dream is to sing Janacek, but I'd want to learn his language first."
She's also candid about the vocal development she's yet to go through. "In the past couple of years my voice has changed a lot. It's become softer, more lyrical, and the top notes are coming more easily – I always had a strong middle range, but was never a really high soprano." At the moment her stage roles are usually Mozart's younger characters – Zerlina, Barbarina – whose vibrant, girlish fizz suits her well. Her latest album (Amoretti, released this week) is a selection of light Mozart and Gluck with the London-based period band Arcangelo. It's sparkly stuff, but Karg is purposefully moving in heavier directions. Over the next few years she'll tackle Debussy's Melisande and Strauss's Sophie and would like to try her voice at Mozart's Donna Anna. Before singing any of Janacek's leading ladies, her decibels will need to grow, "but that comes with age", she says, straightforwardly, and gives herself a good 10 years to realise that dream.
"It's one thing singing a big role once or twice, but rehearsing and performing it for months can be very damaging if you're not ready."
These days Karg divides her time roughly half-and-half between the opera house and the concert stage, and says the two disciplines are excellent training for each other. "Whether I'm in an opera house, church or lieder recital, it's always my same voice. As long as you get into the music, the right sound will come intuitively." Most promising, perhaps, is the list of singers whom Karg says she listens to for inspiration. They are "instantly recognisable – who have something distinctive and eccentric to them". So Luciano Pavarotti ("his voice was so natural, so easy, so touching"), Callas, Sutherland and Schwarzkopf make the roll call. "It's not necessarily beauty I listen out for, because beauty alone gets boring. Some notes are ugly, and should sound ugly."
For the Queen's Hall she's devised a programme of Strauss, Faure, Debussy and Poulenc – a dreamy line-up of thematically linked songs that, with stalwart Malcolm Martineau at the piano, leaves little scope for that desired ugliness. Watch this space.
Christiane Karg is at the Queen's Hall, Edinburgh, today.