April begins with a bang. The Royal Opera House broadcasts Wagner's Siegfried — the third chapter of his epic Ring Cycle —, and if last night's Tristan is anything to go by, you may need to lie down afterwards. Few operatic experiences match the sheer scale and wonder of Siegfried, and with a cast of this calibre, it promises to be an epic in its own right, not merely a footnote to the Met's magnificent Tristan.