The current obsession with supposed authenticity overlooks one very important feature of baroque music performance - its extreme flexibility in the inter-changeability of instrumentation.

There was always music in the Bach household. Perhaps it would be in their family room, just Bach, his wife and sons. More likely however would be a gathering of local musicians in the large room on the upper floor between Bach's apartment and the Thomas School, shared interchangeably for Bach's family gatherings with local musical friends, or rehearsals by the school choir for Sunday performances.

Leipzig was a relatively small community, everyone within the city walls knew everyone else, with the local musicians, amateur and professional, being a special group within a group. They would meet in the Bach home irregularly but frequently, together with visiting musicians too - Bach's son Wilhelm Friedemann recounts that no visiting musician of repute ever consider visiting Leipzig without calling on Bach to pay his respects. Music was work - practice for a Sunday aria perhaps - it was conviviality, and it was simple pleasure to pass the evening.

As local musicians gathered in the evenings in the large music room, already equipped with several keyboard instruments, plus a selection of strings, woodwind and brass belonging to Bach and the School, there would be no shortage of music to try out.

Forkel, Bach's first biographer, who drew heavily on the reminiscences of Carl Philip Emmanuel Bach, states that Bach composed the Six Trio Sonatas for Two Keyboards and Pedal (für zwey Claviere und Pedal) in order to perfect the pedal technique of his son Wilhelm Friedemann, an objective which, as Forkel adds, appears to have been admirably achieved. They would no doubt have been well-practised - and frequently heard in the Bach household, performed on the family's pedal-harpsichord, or perhaps a pedal-clavichord. So why not perform these using the instruments of chamber music - and give Wilhelm Friedemann a rest!

The Trio Sonata is very much a "Baroque" form, if not a Baroque invention. A three- or four-movement piece, tuneful and light, suitable for family home entertainment, the Trio Sonata normally featured two treble instruments: for example, violin and flute or oboe, with a bass instrument and harpsichord to fill out the harmonies. Instruments used would be whatever was available. In the present performances we hear lute, harpsichord, oboe, and viola in various combinations.

These mixed performances certainly show the well-known Trio Sonatas in a new light. For comparison we also offer them played on Silbermann organs, BACH 744, as well as on the pedal-harpsichord, BACH 759.