After taking Friday night off to be just a regular member of an audience for a change (I joined the sold-out crowd for Bill Maher's often wickedly funny socio/political analysis at the Hippodrome), I checked out two decidedly different musical experiences over the weekend. On Saturday, I caught the penultimate performance of "Zippy the Pinhead: The Musical" at the Theatre Project; the next afternoon, a block away at the Meyerhoff, I heard the Baltimore Symphony perform an absorbing program of Ravel, Prokofiev and Shostakovich. From the "Zippy"-diculous to the sublime.