“The Atlanta Symphony Orchestra brought its 2020–21 Behind the Curtain concert series to a joyful, yet peculiarly poignant conclusion,” writes Mark Thomas Ketterson in Monday’s (6/14) ArtsATL. “The event marked the house return of the largest contingent of instrumental forces heard at Symphony Hall since COVID-19 arrived—all in excellent form under Robert Spano, … making his final appearance as the orchestra’s music director…. Mahler’s Symphony No. 4 had been announced in a reduced chamber version, but the easing of pandemic restrictions happily opened the door for a performance of the full score…. The thrill of hearing the symphony in full orchestration was abundantly clear as the players coursed through the third movement’s solemn march and mammoth climaxes…. The concert was creatively presented for the screen with projections of … sepia-toned suggestions of the cosmos, which then burst into vivid color with the final movement’s celestial imaginings…. The unexpected allowance for a full cadre of performers onstage just as this challenging season reached its finale … felt almost mystical… We are still here, and the music is, too.” Also on the program was Samuel Barber’s Knoxville: Summer of 1915 with soprano Jessica Rivera.