MMMbop" isn’t really on par with a classical concerto, but it’s catchy and was composed by teenagers. It demands some respect. And look where those teens from the ‘90s are now: performing with the Pittsburgh Symphony Orchestra. Hanson will be making its PSO debut for Hanson String Theory, Live with the PSO. The show is a “musical manifesto,” complete with new and well-known works from this band of brothers. The Heinz Hall performance has been arranged by composer David Campbell, and it marks Hanson’s 26th anniversary.