In a week that sees Proms visits from two major American orchestras, it fell to Manfred Honeck and the Pittsburgh Symphony Orchestra to raise the curtain for their blue-blooded “Big Five” colleagues the Philadelphia Orchestra. With Tchaikovsky featuring large in both programmes comparisons are only natural, and it will be interesting to see what response Thursday night offers to an energetic but at times rather unsubtle evening of music from Pennsylvania’s “other” orchestra.