In a server apparatus, a storage section stores musical composition data representing a plurality of musical compositions. A transmission section transmits musical composition data which represents a first musical composition to an electronic musical apparatus via a communication network in a streaming manner, such that the electronic musical apparatus can reproduce the first musical composition in realtime basis. A reception section receives operation data from the electronic musical apparatus, the operation data representing a user operation of the electronic musical apparatus performed in response to realtime reproduction of the first musical composition. A control section selects musical composition data representing a second musical composition based on contents of the operation data, such that the second musical composition matches a skill of the user to operate the electronic musical apparatus, and controls the transmission section to transmit the selected musical composition data of the second musical composition to the electronic musical apparatus in the streaming manner, whereby another user operation can be performed in response to the realtime reproduction of the second musical composition.