To the untrained ear they sound amazing.... but conductor Eleri Watkins isn't letting the children of Denbighshire's Youth Choir rest on their musical laurels. Next week they swap a school hall in Rhyl for a six-minute slot in the special Schools Prom at the Royal Albert Hall - and instead of a chorus of parents at the back, there will be a space holding a thousand keen listeners instead.
The pressure is on to perfect their two songs and to practise their stagecraft - how to enter the stage, how to leave and the best way to bow. The youngsters are excited and a bit apprehensive about their performance - they'll be singing two songs in Welsh in the centre of a London stage so big you could almost get lost in it.
It's an honour they've all worked for, with parents and choir members packing bags at a local supermarket to raise money to pay for the trip.
Right now, they're packing their own bags and will hit the spotlight next Tuesday.
VIDEO: Watch the choir singing 'Ysbryd y Nos'.