When you hit the 'GO' key, you enter PLAY mode. Music will play at the established tempo. Therefore if no tempo has been set with either PLAY or CRUISE, the music will perform on autopilot at the preprogrammed tempo. If you have established a desired tempo with PLAY or CRUISE and then hit the 'GO' button, Sinfonia will continue playing at the tempo you have set. Just like cruise control on a car, you can jump in 'tapping' at any time if you need to change the tempo. NOTE: The Sinfonia calculates the tempo from the last two taps you make (including the tap on the 'GO' button. You must hit the 'GO' button in the same tempo as the PLAY, otherwise, you may find yourself in a tempo you didn't intend!