Eclectic collaboration between guitarist William Coulter and violinist Edwin Huizinga ranges from Bach to Vivaldi; tango to Celtic tunes; traditional Bulgarian to American fiddle tunes and waltzes at Camden Opera House, 29 Elm St. Choose-your-own reserved seats ($10, advance purchase encouraged) via camdenoperahouse.com or 236-3154) plus free Facebook Livestream. Sponsored by Studiomind.