In 2004, Simpson recorded the violins on the album "Stand Up" for the Dave Matthews Band. In 2005 she toured Italy with the North African/American band, Kantara, which performed Arab-Appalachian music. In 2006 Simpson was invited to tour with the progressive rock band, Jethro Tull, as a guest soloist. She admitted: "I had to Google 'Ian Anderson' when he first contacted me." Anderson later said of Simpson: "Unlike many of her fiddlin' friends from the classical world, Ann Marie has cultivated considerable improvisational abilities but still retains her music theory and the ability to play set parts and orchestrations."