Rivers tend to be men, but Father Rhine only had daughters to entertain him in his dotage. Those women are summoned up in this amorphous album delivered by the female singers of Ensemble Pygmalion, four horns and a harp. It’s a bold attempt to put the phallic symbols of German Romanticism – thrusting symphonies, macho concertos – to one side and explore a softer, damper type of mood music by Wagner, Brahms, Schubert and Schumann.

If there is a feminist slant here, the point isn’t laboured. The musicians are actually co ed: the harpist is a man (Emmanuel Ceysson, who describes himself as ‘the enfant terrible of his instrument’, a position for which there must be few applicants), and so are three of the hornists and the conductor, Pygmalion’s Raphael Pichon. ‘Rhinemaidens’ is apparently the first of three Pygmalion albums which will gradually move forwards in musical history; the second will explore male voices and the third feature mixed voices.

Also saving the album from being a literal damp squib is the other major leitmotif. Canons run through nearly all the pieces, reinforcing ideas of flow – fluvial or otherwise – and development. These begin, appropriately, right at the bottom of the Rhine, in the Prelude to Das Rheingold, the horns’ elemental calls buttressed by growling double basses, the wordless cries of the singers building to a shimmering climax. Wagner’s Ring returns in Siegfried’s Horn Call and his Funeral March, orchestrated for four horns (bouncily done, but a bit Bridlington bandstand rather than funeral pyre in Westphalia), and finally the Rhinemaidens’ lament from Götterdämmerung.

Yet those are really atmospheric waymarks to guide you through rarer treasures by the other three composers. Siegfried’s horn doesn’t summon a slobbery dragon but Brahms’s folksong (in canon, of course) ‘Wille, wille will der Mann ist kommen!’, followed by Schubert’s ‘Ständchen’ for female chorus, harp and mezzo-soprano (Bernarda Fink), a real Biedermeier house-party extravaganza. In a section inspired by mourning, the Rhine’s waters dissolve into the tears of Schubert’s stark ‘Lacrimosa son io’, Schumann’s double canon ‘Die Capelle’, immaculately delivered, and back to Schubert for the remarkable ‘Coronach’, a keening lament to words by Walter Scott. With the voices now accompanied by declamatory horns and harp, the ballad has an authentically Gaelic feel without succumbing to new-age whimsy.

Indeed, it’s the discipline of the delivery – whether it’s the firm, resonant voices or punchy horns – that impresses most here. Both passionate and precise about their subject matter, Pygmalion have discovered watery depths to familiar composers, and have certainly not sold us down the river.