No composer-conductor is more sensitive than Pierre Boulez to the divergent responses to Wagner’s Tristan that can be traced in Debussy’s opera and Schoenberg’s symphonic poem, both derived from Maeterlinck’s Pelléas et Mélisande. The more determinedly (since the 1970s) Boulez as conductor has engaged with late-Romantic German music as well as with Debussy, Ravel and Messiaen, the more difficult – the hypothesis runs – he has found it to compose anything of substance himself. But there is no hint of resentful coolness or distancing in these performances. Travelling to Japan with the Gustav Mahler Jugendorchester in 2003, Boulez at 78 tapped into levels of youthful intensity, even abandon, that his earlier readings of such music had tended to avoid.

Schoenberg’s first major orchestral score benefits greatly from not being allowed to sprawl, but keeping the music’s richly orchestrated flow under a tight rein doesn’t diminish its expressive power and Boulez brings out the best aspects of its formal flexibility and textural richness. In the final stages he even allows himself to broaden the tempo at a place not asked for by the composer without sounding contrived; and, while a studio-based recording might have found even more subtlety and sumptuousness in the opulent instrumentation, this reading is a fine complement to Boulez’s earlier Chicago recording of the work. As curtain-raiser the Prelude to Act 1 of Tristan grows to an ecstatically impassioned climax before the beautifully shaped dying fall of Wagner’s concert ending achieves an effect of well-nigh Debussian understatement. The rapport between seasoned maestro and youthful players has never been more satisfying.