'When I started playing as a child, I wanted to change the world,' says brilliant violist Maxim Rysanov. He smiles. 'It sounds grand, I know, but that's how I really felt.'

Not the whole world, you understand, just the part that believes the viola is somehow inferior to the violin. And, so far, he's on course to fulfil his ambition. The 29-year-old has a tone so warm it would melt flint and an expressiveness so beautiful it's almost indecent.

His recital disc with pianist Evelyn Chang on the Avie label is a corker, and he's the latest person to join the prestigious BBC New Generation Artists scheme. If anyone looks as if they might be able to push the viola more firmly into the limelight, it's Rysanov.

The problem is the lack of repertoire. That's why his turn in the Mostly Mozart festival, on July 19, won't see him playing a flashy solo concerto, but instead performing as one of the group of soloists in Bach's Brandenburg Concerto No.6. But the London-based Rysanov isn't worried.

'I love Bach's music. I think of it like a building made of glass that you can look through. It's not about thick, heavy, monumental walls. It's about transparency and light.' That view was a change from the style he was taught in his native Ukraine, and then Moscow.

'I learned so much when I came to the Guildhall in London,' he says. 'I became a musician, rather than a player. My teachers opened the doors to my own mind for me.' Remember the name: Rysanov is one to watch.

If Bach's not your bag, there are many other temptations on offer at the festival, which runs for the next four weekends at the Barbican. A bevy of fiddlers will be put through their paces, including two BBC Young Musician Of The Year winners. The sensational Nicola Benedetti plays Mendelssohn's Violin Concerto tomorrow and Jennifer Pike plays Mozart's Violin Concerto No.3 (August 3). One particularly exciting concert sees the masterly Lisa Batiashvili perform the British premiere of a new violin concerto by Magnus Lindberg (July 27). The conductor is Thomas Dausgaard, whose recordings with the Swedish Chamber Orchestra are thrillingly good - crisp, clean, fleet.

'It's a piece that is full of light, of Nordic light,' Dausgaard says. 'It's weighty and broad and beautiful, not a show-off concerto.' All this and free events, talks, improvisation sessions and even fireworks. Mostly Mozart is mostly irresistible.

Mostly Mozart, tonight until Aug 4, Barbican, Silk Street EC2, various dates and times, £8 to £29. Tel: 0845 120 7550. www.barbican.org.uk/mostlymozart Tube: Barbican/Moorgate.