Having completed his Beethoven project, Ronald Brautigam now turns his attention to Schubert, and this, his first foray into his solo keyboard music on disc, is typically engaging and thought-provoking.

He plays a Paul McNulty fortepiano after Conrad Graf, c1819, so you can immediately expect the instrument to be a thing of beauty. That, combined with Brautigam’s probing musicianship, pays dividends in many ways: in the first Impromptu of D899, for example, there’s a transparency to the sound so that even the most vehement writing (eg from 5'10") never becomes overbearing, while Schubert’s cherishable shift to G major (6'47") has a warm simplicity to it. The instrument also comes into its own with textures such as those found in D899 No 2, with its stream of triplets in the right hand set against the simplest of left-hand backdrops, Brautigam knowing just how far he can push Schubert’s ben marcato direction in the minor-key inner section. If the lustrous G flat major No 3 doesn’t attain the yearning quality of the finest (here I find myself going back to more modern instruments in the hands of Radu Lupu and Edwin Fischer – the latter bringing a heart-rending lieder quality to the line), there are no doubts about the fourth, Brautigam reminding us how much of it is marked is piano or pianissimo, while in its Trio section the focus on tenor and alto registers is beautifully illuminated on the McNulty, the shift back to the opening material completely inevitable-sounding.

In the second set of Impromptus Brautigam has fascinating competition with Andreas Staier, playing a Christopher Clarke copy of a slightly later Graf (1827, so exactly contemporary with the music). Both musicians combine intellectual rigour and bold imagination: predictably the large-scale canvas of the F minor (No 1) has tremendous presence; if there’s a caveat here, it has to do with instruments, Brautigam’s fortepiano sounding just a little thin at its topmost reaches (eg 2'25"), compared to the more glistening quality of Staier’s. The graceful Second comes across winsomely, and the variation-form Third is full of imaginative touches, Brautigam choosing for its theme an easeful tempo, subtly drawing the melody from the accompanying figure in Var 1, the switch to the minor (Var 3) properly turbulent without becoming shouty. If there are some reservations to Var 2, which could be more playful, and Var 4, which is a little effortful – certainly compared to Lupu and Fischer – the last variation has a seductive ease to it. Brautigam brings to the final Impromptu a driving, dancelike quality and, to its middle section, an almost improvisatory feel to the scalic writing, relishing Schubert’s luscious key sequence before the F minor vehemence of the final Più presto section. What is consistently compelling about these performances is the way Brautigam and his instrument allow us to look under the bonnet of the music, and to wonder anew at Schubert’s genius.