To dream of an orchestra represents situations where you feel good about various factors working well together. Integration and harmony. Passionate expertise.
Negatively, an orchestra may reflect anxiety or stress about being required to make a situation with various factors work perfectly. Multiple areas of your life that you feel pressured to make work flawlessly. Exhausting yourself using your skills to keep other people perfectly happy.
Example: A man dreamed of hearing an orchestra. In waking life in the middle of a dog sled race. The orchestra may have reflected his feelings about all the dogs working well together at the same time during the race.