It’s difficult to escape a sense of gimmickry with this, though its aims are ostensibly serious. Exploring the range and versatility of the countertenor voice, it brings together five very different singers, whose reputations are all founded on their interpretations of baroque works originally written for castratos. The results are variable. Max Emanuel Cencic has been in better voice than he is here, and not everyone will care for the loss of tone quality in Valer Sabadus’s lower registers, though his coloratura technique, complete with pinprick staccatos, is formidable. Vince Yi is at a better advantage than his recent appearance in The Indian Queen at ENO; his super-refined delivery works wonderfully against Yuriy Mynenko’s persuasively virile athleticism. Xavier Sabata is the least overtly flamboyant of the five, though his dark alto and exceptional psychological insight make his arias, by Handel and Porpora, particularly outstanding.