Yamaha have taken a weighted keyboard from their latest digital pianos, added high-quality piano samples and Motif sounds, and thrown in a playback sequencer and arpeggiator, and master-keyboard facilities. Left to simmer, the S90 is the result...
It seems simple enough — take the successful Motif workstation, remove the keyboard, and release it as a more affordable rack unit. But there's lots more to the Motif Rack than meets the eye...