I think Sparky got it right:
"The Callaways" series, "Jean & Jim", Chapter 33
Turning to Susie he asked, "Is there any more to the music than what we just heard?"
"There isn't, sir, but there could be," Susie replied.
"What does that mean?"
"It could scale up to a full symphony."
"And you could do that?"
Author: Morgan
Story: Jean & Jim
Otherwise it could be Kristin from the same author:
Chapter 18:
We learned that Susan was scheduled to conduct her First Symphony with the New York Philharmonic on Saturday. Strangely believe it, tickets were found for the composer/conductor's relatives and friends.
Since what I know about symphonic conducting would rattle on the head of a pin, I didn't realize there was anything out of the ordinary when Susan spent only a single afternoon rehearsing with the orchestra.