“The Denver School of the Arts has, in 16 years, grown into one of the most exclusive public schools in the Rocky Mountain region, admitting less than a third of the students who apply to get in every year. In auditions, artistic prowess trumps grades, determination, hardship and whether applicants even have a Denver address. [But] some community advocates and school-board members are concerned that the school is an oasis with a figurative moat around it; those who can afford private lessons are likelier to make the cut.”