To dream of a piano represents mastery or total control over your emotions. Feeling that a situation is absolutely perfect.
You may be practicing self-control or training yourself to give up certain feelings. A piano may also show up in a dream when you listening to certain types of music to control your mood. Sexual abstinence or reducing sexual activity may be an issue.
Consider the location of the piano to gain insight into how your emotions are being controlled. A piano in an office may point to emotional self-improvement and a piano in a bedroom may reflect emotional control over private or sexual issues.
Negatively, a piano may reflect too much confidence in your ability to master a problem. Superior mastery of a skill for immoral purposes.
Example: A woman dreamed seeing someone playing the piano. In waking life she was very confident in herself being perfectly faithful to God. She felt she had mastered her ability to make God happy with the large amount of persistent praying and good behavior.