By now, nobody in Philadelphia should be surprised that conductor Donald Nally is making a hard-to-explain departure: Lyric Opera of Chicago is expected to announce this week that chorus master Nally is leaving at the end of the 2010-11 season to spend more time with his Philadelphia choir, The Crossing.

What wasn't said: He's leaving one of the top positions of its kind (Chicago's previous chorus master is now at the Metropolitan Opera) - with uncertain financial prospects.