Ernst Krenek wrote his Reisebuch – the text as well as the music – in a few weeks in the summer of 1929, shortly after making the Alpine journey that inspired it. Though comparatively few singers have tackled it, it ranks among the finest of 20th-century song-cycles, a wide-ranging, complex work, rich in emotional and political resonances. In essence, it’s a meditation on the state of interwar Europe that revisits the landscapes of Austro-German Romanticism and observes their decline with a mixture of sardonic objectivity, sorrow and pre-absurdist humour. The Alps are awash with tourists ‘seeing nothing, because they must write postcards’ (Krenek himself is one of their number, which deepens the irony): a cemetery admits the prurient to its charnel house for a fee, while the inhabitants of a monastery turn out to be surreptitious drinkers. Near the midpoint, the viewpoint widens as the evocation of a distant ‘bloody clown’ (Hitler) reminds us of the growing threat to fragile democratic certainties.

The score is comparably allusive, poring over musical tradition while seeking to extend it. There are repeated echoes of Schubert, Schumann and Mendelssohn, though Krenek cannily avoids direct quotation. The piano writing, meanwhile, sometimes takes on polyphonic overtones that peer back though Brahms to Bach. The harmonic language can be harsh: Krenek keeps within the bounds of tonality but irony and anger often lead to dissonances as fierce as anything in Schoenberg or Berg.

Florian Boesch and Roger Vignoles gave a revelatory performance of the work at the Wigmore Hall in January 2015, returning to it in the studio last October, and it would be fair to say that Boesch has done nothing finer on disc. This is exceptional Lieder singing, fusing line, text and dynamics into an indivisible whole, all of it delivered with a conversational intimacy that is often breathtaking. The emotional ambivalences are finely projected, as sadness, dismay and anger are repeatedly undercut by self-deprecating wit and humour. The final song equates travel and wandering with the essential rootlessness of the human condition: Boesch sings it in a mood of resigned calm, beneath which one still detects a last quizzical twinkle of irony. Vignoles, meanwhile, matches his every shift of mood with playing of great control, refinement and subtlety. It’s an outstanding achievement and hard to follow, but as a filler there are four early songs by Zemlinsky at his most darkly Romantic, all of them quite beautifully done.