Emanuel Bach, second son of JS, was famous for his rhapsodising at the clavichord in his Hamburg home. As the visiting English music historian Charles Burney recalled: ‘He grew so animated and possessed, that he not only played, but looked like one inspired.’ We can imagine Emanuel creating these six string symphonies in the same spirit. Wildly eccentric on every level, they often sound like inspired fantasy-improvisations writ large. To make the point, Marcin Świątkiewicz interleaves the symphonies with three of Emanuel’s wayward keyboard fantasias, plus a brief improvisation of his own, to create what he calls an ‘Instrumental Theatre of Affects’ in two acts. The concept works well. We can guess that CPE would surely have approved of the shock created when, say, the C minor Fantasy (from the Sonata Wq63/6) tumbles in on the remorseless close of the B minor Symphony No 5.

In the Fantasias (two played on the fortepiano, one on the harpsichord) and his own CPE pastiche improvisation, Świątkiewicz is in evident sympathy with music that unfolds as heightened speech. The slow movements of the symphonies mine the same vein of Empfindsamkeit (roughly, ‘sensibility’), with moments of soulful or brooding lyricism constantly threatened by alien harmonies or disruptive dynamics. Świątkiewicz and the nine strings of Arte dei Suonatori shape and time this music with an understanding of its distinctive, often disturbing rhetoric. Most disorientating of all is the Adagio of the C major Symphony, No 3. From the stabbing open chords, the Polish players vividly catch its spirit, phrasing the fragile violin dialogues with a singing eloquence and precisely observing Bach’s detailed dynamics, from ff to pp, with every shade in between. For me Świątkiewicz's prominent spread chords slightly detract from the beauty of the melody in No 5’s Larghetto. But this is personal taste.

Emanuel’s fast movements demand a disciplined craziness. They get just that from the virtuoso players of Arte dei Suonatori, eagerly propelled from the harpsichord by Świątkiewicz. Antiphonal violins vie in desperation in the volcanic finale of the B minor. Yet amid the hyperactivity Świątkiewicz and his players are happy to bend the pulse in response to moments of pathos and questioning, as in the sighing lyrical fragments in the outer movements of No 2. In the opening Allegro of No 4 in A major the players delicately caress the fluttering arpeggios before the inevitable disruption arrives.

Among previous recordings of these no-holds-barred symphonies, each one a pocket dynamo, the standouts are Trevor Pinnock with the English Concert and Alexander Janiczek with The Orchestra of the Eighteenth Century. Both are on a larger scale than this new version (Pinnock uses around 18 strings, Janiczek 24), with gains in sheer power in some of the fast music. The corporate virtuosity of the Orchestra of the Eighteenth Century, especially, is thrilling. Pinnock’s pioneering recording crackles with the excitement of discovery. But Świątkiewicz matches both rivals in visceral energy, while his chamber forces create a uniquely intimate expressiveness in the slow movements. If you’re wavering, the inclusion of the Fantasias, notching up the playing time to 85 minutes, may clinch it.