Sydney Symphony’s Cocktail Hour series is an intimate affair curated by a member of the orchestra and usually involves a handful of their colleagues.

But when it comes to horn player Euan Harvey’s turn to put on a show at Sydney Opera House’s 200-seater Utzon Room he calls on 15 instrumentalists for a program of works by three of Romantic music’s biggest hitters.

Euan Harvey. Photo © Daniel Boud

You don’t normally hear the words “chamber music” and Wagner in the same sentence, but he did compose what must go down as one of the loveliest Christmas Day gifts in history, Siegfried Idyll, as a triple celebration for his wife Cosima – her birthday, the recent legalisation of their marriage and the birth of their third child, Siegfried.

It was first performed as a surprise in 1870 with a small band of musicians arranged on a staircase at the couple’s villa at Tribschen on Lake Lucerne, Switzerland.

Part of its legend is the short trumpet part that conductor Hans Richter had to teach himself to play in secret on a boat on the...