"BACHBUSTERS." J. S. BACH: "ITALIAN" CONCERTO; TWO- AND THREE-PART INVENTIONS; VARIOUS CANONS; TOCCATA AND FUGUE IN D MINOR; "JESU, JOY OF MAN'S DESIRING." Don Dorsey, digital and period synthesizers. Telarc CD-80123. "All music," said Pablo Casals, "is a succession of rainbows." But this electronic performance has flattened the rainbows of Bach into Tarmac. With one exception--the slow movement of the "Italian" Concerto--these recordings avoid any trace of humanity or expression. Rhythms and speeds are straitjacketed by the synthesizer. The finale of the "Italian" Concerto is captive to a chilling drumbeat. The first Two-Part Invention rattles forward without the slightest bending of rhythm. The mighty flourishes which announce the Toccata in D minor are rushed through, as if a computer had deleted the fact that they are among the most sublime passages in all music.