It contains several features beyond those offered on Kawai K1, adding resonant filters and a DAC PCM wavetable.
The K4 incorporated a new type of synthesis called Digital Multi Spectrum.
Interestingly, the K4 uses a system that splits 16 bit samples between two read only memory (ROM) chips, while reserving a third chip for 8 bit sound samples that naturally have more noise (such as cymbals, snares, and other noisier percussion) in order to have more functionality for a cheaper manufacturing cost.
[4] A 2U rack mounted module was also produced by Kawai.
[5][6] It has six separate audio outputs in addition to standard left/right stereo outs and a headphone socket.