This violinist and songwriter gained national attention in March 2016, winning NPR’s Tiny Desk Concert contest. Gaelynn Lea Tressler has been on the move since then, in hot demand on the concert circuit. This year’s Homegrown performance will be a preview of music from a fourth album, due in September. It’s what Tressler calls a “radical departure” from past efforts, which mostly included haunting vocals backed by violin and a looping pedal. The current crop of songs are more complex, requiring the recruitment of a backup band consisting of Al Church, Dave Mehling, Martin Dosh and Andrew Foreman. Longtime collaborator Alan Sparhawk is also prone to getting in on the action.