This previously unreleased live performance of Bach’s Well-Tempered Clavier Book 1 took place in March 1987, just one month after Keith Jarrett recorded the 24 Preludes and Fugues in the studio for ECM. Although his straightforward and often matter-of-fact Bach-playing proves fairly consistent between both versions, sonic considerations may factor into how one perceives the interpretations by way of the smooth and rounded patina conveyed by the studio engineering versus the closer, leaner, more intimately scaled concert recording.

For example, the C major Fugue’s strettos seem more sharply contoured live than in its relatively generalised studio counterpart, whereas the suave studio C minor Prelude turns notey and grey in front of an audience. The studio ambience undermines the G minor Prelude’s chains of trills, which gain definition thanks to the live traversal’s tighter pickup. Jarrett’s fluidly understated studio A minor Fugue retains its basic tempo throughout, whereas the pace slightly speeds up in the live version. On the other hand, the relatively dutiful and square studio B minor Prelude comes out of its shell a month later, replete with an altogether lighter touch and arching line on Jarrett’s part. The leaner live engineering also conveys a sense of transparent linear interplay in both the B flat minor Prelude and Fugue.

Other interpretative variants in the present recording can be ascribed to Jarrett’s free will, or perhaps it’s the adrenalin talking. How else might one explain his C sharp minor Prelude’s newfound freedom and rhetorical flexibility? The A minor Fugue remains buoyantly understated, except that the tempo gets a tad faster as the music progresses (better than the opposite!). The briskly dispatched A major Fugue’s cross-rhythmic phrases become less emphatic and more conservational now, while both the F major Prelude and Fugue truly take wing.

For all of Jarrett’s seriousness and concentration, I miss the colour, the nuance, the finely honed degrees of touch and the range of expressive variety characterising a good number of Book 1 piano recordings; Ewa Pobocka’s extraordinary recent release is a case in point.

Then again, can the greatest Bach pianists deliver a totally improvised solo concert from scratch on Jarrett’s stunning creative level?