It's so difficult playing Bach's solo music on a bass viol, writes Susanne Heinrich merrily, that "it is unlikely to start a trend". Obsessed with the six violin sonatas and partitas since a young age, this leading viol player has appropriated three of them for her own instrument, which is larger, deeper, with more strings and a sound of intimate intensity. As she notes, the viola da gamba (bass viol) is best suited to slow, contemplative music, of which there is plenty here. Sometimes she has had to transpose to another key, or rearrange the way a chord is spread. The results are hushed and illuminating. The great Chaconne from the D minor partita is heard as through a glass darkly.