In the U.S., the music was being developed to create a more sophisticated sound,[citation needed] moving beyond just drum loops and short samples. In Chicago, Marshall Jefferson had formed the house group Ten City Byron Burke, Byron Stingily & Herb Lawson(from "intensity"). New York–based performers such as Mateo & Matos and Blaze had slickly produced disco house tracks. In Detroit a proto-techno music sound began to emerge with the recordings of Juan Atkins, Derrick May and Kevin Saunderson.

what group did Marshall Jefferson form?