Although it was once assumed that J.S. Bach wrote these 8 Concertos for harpsichord to learn the finer points of the Italian concerto form, it is now thought that he adapted these pieces to increase his performing repertoire, rather than to perfect his compositional technique. These works are based on six string concertos by Antonio Vivaldi, an oboe concerto by Alessandro Marcello, an anonymous concerto, and a Presto movement by Prince Johann Ernst von Sachsen-Weimar, and were expanded and embellished by Bach to serve as vehicles for a virtuoso performer with supporting basso continuo. Harpsichordist Naoki Kitaya and his small retinue -- Rainer Zipperling on cello and viola da gamba, Thomas Boysen on theorbo and Baroque guitar, Daniel Oman on colascione, and Naoko Matsumoto on continuo harpsichord -- deliver forceful and energetic performances, though they often sound a bit bottom-heavy and thickly textured, as might be guessed from the ranges of the instruments listed. Part of the thundering quality of this disc is due to the bold playing, which is quite accentuated and brusque, but the recording itself seems excessively boosted and close to the performers, overcompensating for the harpsichord's small sound in such a setting. So if the volume is adjusted to a reasonable mid-level, Kitaya's vigorous playing will be easier to appreciate and the continuo will seem less obtrusive and booming.