Korg X5 90's Polyphonic AI2 Synthesiser W/ Effects MIDI & More!Korg X5 90's Polyphonic AI2 Synthesiser W Effects MIDI & More! The Korg X5 is a digital synthesiser from the mid 1990s that combines Korg's AI2 synthesis engine with a compact, portable design. It features a 61 key keyboard with velocity sensitivity, 8 part multitimbrality, and a General MIDI soundset, which makes it versatile for various musical styles. The X5 includes over 340 multisampled sounds, which cover a wide range of instruments and effects.