In 1990 he began performing regularly with a Chicago area folk-rock band called Uncle Buffalo's Urban Mountain Review before joining Hairball Willie in 1991.

With John on guitar, violin, and vocals, Hairball Willie performed around the Midwest and released several recordings, including a full-length studio CD, Just Defying Gravity.

In 1997, he co-founded the Dark Star Orchestra, which was originally intended to be a one night a week Dead cover band formed by deadhead musicians.

This led ultimately to the formation of the Mix with Melvin Seals, Greg Anton, Jeff Pevar, and Kevin Rosen.

In addition to his work with Dark Star Orchestra and Furthur, Kadlecik has continued to perform on his own in the Washington D.C. area, both solo acoustic and as the leader of small bands, including projects like Firewheel.