“Wall to Wall Opera,” a 13 hour orgy of things operatic, inhabits Symphony Space beginning at 11 a.m. on Saturday. Among the festivities is a master class in bel canto interpretation by Renata Scotto, but the moment La Cieca most eagerly awaits will arrive courtesy of Encompass Opera Theatre. We are promised a performance of “The Silver Aria” from the haunting opera by John LaTouche and Douglas Moore, The Ballad of Baby Joe.