Conductor Andrew Davis won’t renew his three-year contract as artistic advisor to the Pittsburgh Symphony. The job was an unusual one for the orchestra. “We are not wedded to this model. It is a new model for an orchestra in America to be trying. We have found parts of it that have been interesting and enlightening and parts that don’t work as well. We will either have to find ways to make it work within the model or work outside of it. We want to do what is best for the artistic future of the organization.”