Ensemble-in-residence at Belgium’s Cultureel Centrum Maasmechelen, the Parnassus Akademie was founded by cellist Michael Gross, best known for his work in Baroque music with Helmut Rilling, in order to re-explore the chamber repertory by juxtaposing the rarely heard with the better known. The ensemble’s debut CD, establishing them as a force to be reckoned with, places three radically different string sextets side by side.

This is the first outing on disc for d’Indy’s Sextuor, a late work (1927) written in semi-retirement after his teaching career was over, though he seemingly relaxed neither his lofty stance nor his fondness for self-conscious infractions of tradition. Rather than thinking in terms of an ensemble of six, d’Indy writes for two string trios who sometimes play together but more often than not shuttle the material antiphonally between one another. In form, it’s a suite, with an Entrée and Divertissement followed by a lengthy set of variations, in which the chromatic chordal theme gradually morphs, a bit too knowingly, into a quotation from the Forest Murmurs from Siegfried. On a disc where the performances are as sharply differentiated as the content, the Akademie play it with a fastidious elegance that belies its technical difficulty.

The contrast with Bridge’s lyrical expansiveness and Schulhoff’s revolutionary anger couldn’t be more pronounced. Bridge’s E flat Sextet, dating from 1912, before wartime disillusionment darkened his style, is done with an opulent richness that obscures neither its complex cyclic structure nor the darker emotions that underscore it. Schulhoff’s 1924 Sextett, which pulls everything from Schoenbergian expressionism to East European folk into a single eruptive whole, is a driven tour de force in which the concentration of the performance matches the extremity of the music, leaving you faintly shell-shocked by the end.

It’s a difficult piece to follow, and the disc works better if you programme the three sextets in reverse order – Bridge first, Schulhoff last. Otherwise, it’s a terrific achievement, and highly recommended.