The basic recipe, time-tested and crowd-pleasing, of the Seattle Chamber Music Society's summer festival remains the same, but it's been undergoing some tweaks over the past few years, some voluntary, some otherwise. Moving from Lakeside School to Benaroya Hall necessitated a change to the popular program of broadcasting concerts outside to picnickers on the Lakeside lawn. Now the society will be going even farther afield by beaming the performances to various city parks (Westlake, Volunteer, and South Lake Union's Cascade Playground). Better yet, one concert (July 25, Dvorak and Tchaikovsky) will be played at Volunteer Park. (Previous Augusts saw additional SCMS concerts at Redmond's Overlake School; not this year.) New artistic director James Ehnes is making a point to include on each of the 12 regular concerts a work new to the festival, including a premiere by Gary Kulesha (July 20) and pieces by pianist/composers Marc-André Hamelin (July 2) and Adam Neiman (July 16 & 18). Other highlights include Astor Piazzolla's Argentine take on Vivaldi's "Four Seasons" (July 6); octets by Shostakovich and Mendelssohn (July 13); and John Adams' Hallelujah Junction for two pianos (July 18).