Things to consider:
1. Is there a musical accompanying device that needs to be considered? When I installed the Baldwin systems, they had a cd player hooked up, with one channel being accompanying music, and the other a "command" track that was sent to the Baldwin player
2. If the customer wants to hear the piano in other rooms, does the piano have an audio out, or will you be using microphones?
3. If you are using microphones, you may want to consider mixing the accompanying track with it.

Good luck.