RICHARD SPARKS on rehearsing with piano:
The basic rule should be to take away the keyboard as quickly as possible. When teaching or observing young conductors I often have to remind them: take the piano away! There are several reasons for this. One is exactly as in Ericson’s example: use only the minimal amount of support so the choir becomes independent. But there is an equally important reason–when the piano is playing you simply can’t hear as much of what the choir is doing. You as the conductor need to know . . . does the choir really know it? Can they find the pitches for the next section on their own? Is that chord really in tune? The sound of the piano can blur what’s happening and your ability to hear it.
I think that’s great advice. Some conductors swear by the importance of never using the piano in rehearsal at all, but I have yet to have that work out in my experience. Any thoughts?