Following a fine Rheingold and even finer Walküre, Naxos’s Hong Kong Ring reaches Siegfried, so often the ‘problem child’ of a complete cycle. Not that it’s a washout as Jaap van Zweden helms this opera as impressively as he has its predecessors. The troubles stem from a mixed cast and a rather variable quality to some of the recorded sound.

Of course, no Siegfried can succeed without vocal heft in the title role and New Zealand Heldentenor Simon O’Neill is on the money much of the time. His bright, if occasionally tight tone proves perfect for a thrilling forging scene and he’s still clearly powering forward in that exhausting final scene, his voice seemingly growing in...