Yamaha's S90ES is an 88-note synthesizer and controller keyboard featuring aftertouch and Balanced Hammer Effect Action, a weighted-action keyboard design that offers an even physical key response from the lower to the higher registers.

The 228 MB(!) S90ES Sound ROM contains a large and versatile selection of sounds from Yamaha's Motif Sound Library, ranging from a 53 MB stereo piano sample with soundboard emulation models, and a realistic acoustic instrument collection, to some really esoteric synth ambiences.

For those captivated with loops and arpeggios, the S90ES's interactive arpeggiator has a total of 1787, available in a wide range of patterns and musical styles.

A rotary encoder and 4 assignable sliders complement the pitch and modulation wheels and large, well-lit screen. A USB port is standard and mLAn support is available as an upgrade option, two factors that increase the life of the S90ES as a viable musical instrument and master keyboard controller for the stage and the studio.