It’s hard to say who will be more nonplussed: rock fans disappointed that Roger Waters’ first move following Pink Floyd’s stunning Live 8 reunion is an opera about the French Revolution, or opera fans fearing any and all incursions into their world by rock musicians. Waters’ “Ca Ira” — based on the original libretto by Etienne and Nadine Roda-Gil and featuring baritone Bryn Terfel, tenor Paul Groves and soprano Yin Huang in a variety of roles — is heavy on the explication, making it a fairly laborious listen. But the issues it deals with — liberty, equality and the tragic indifference of the ruling class — are as relevant today as in the 18th Century.
