In 1985 at the tender age of 23 he was asked join the classic rock band Chicago as their new tenor lead vocalist and bass player replacing the iconic voice of Peter Cetera.
His first album with the band, "Chicago 18", featured his lead vocals on one of the band's biggest hit singles, "Will You Still Love Me". He went on to co-write and sing lead vocals on another massive hit "What Kind Of Man Would I Be". He also produced and co-wrote the title track of "Now - Chicago 36" released in 2015.
Jason has appeared on countless television shows including his outstanding performance of "25 or 6 to 4" on the "Rock and Roll Hall of Fame" induction ceremonies inducting Chicago into the class of 2016.
He has also appeared as a background singer and bassist on many recordings for artists such as Elton John, Neil Diamond, Poison, Cher, Kenny Rogers, Gino Vanelli, Christopher Cross, The Commodores and many more.