Catching the eye of younger generations has long been high on the Cleveland Orchestra's to-do list. Their greatest success to date centers around the after-show concert scene they introduced last year on Friday nights. Following an abbreviated performance of the weekend's classical lineup, guests are invited to stick around and mingle at a post-concert party in the gorgeous Severance Hall lobby. Renowned world-music percussionist Jamey Haddad mined his Rolodex to curate the series; last year he brought in the likes of Cyro Baptista's Beat the Donkey and flamenco guitarist Juanito Pascual with percussionist Marcos Santos, each of whom rocked the place like not even the most rousing of orchestra performances can. Add food and drinks, and ladies and gentlemen, this looks like that Holy Grail of the non-profit arts sector: Genuine audience development.