A plurality of tone generator devices include respective waveform data memories, and each of the waveform data memories is exclusively usable by the corresponding tone generator device, not sharable with the tone generator device. Once event information indicative of a tone to be generated is received, a selection is made, from among the plurality of tone generator devices, a particular tone generator device to be used for generating the tone corresponding to the event information. The selection can be made by determining, with reference to a table, in which of the memories of the tone generator waveform data to be used are stored. For example, first waveform data corresponding to a first pitch range and second waveform data, differing in waveform characteristic from the first waveform data and corresponding to a second pitch range, are stored in the waveform data memories corresponding to different ones of the tone generator devices. The event information is delivered to the selected tone generator device so that a waveform signal of a tone indicated by the received event information is generated by the selected tone generator device.