'EXTREME MUSIC LENDS ITSELF WELL TO EXPERIMENTAL ARRANSEMENTS': In an extraordinary double album, former Emperor guitarist Ihsahn delivers new material in two contrasting versions: metal and orchestral. 'It was a perfect match,' he says, 'because my guitar had the same tuning as the cellos!'

Heavy metal and classical music may appear to be diametrically opposed, but there's a lot to be said about the shared kinship between them. And few understand this as well [...]