The YAMAHA PortaSound PSS-790 is adopted with a unique synthesis "Advanced Wave Memory (AWM)' so that you can perform with a wide range of natural to hyper-natural sound qualities. Additionally, the Vector Synthesizer function enables you to carry out time variance of a tone with controlling mixing ratio of any 4 AWM Voices you select. Furthermore, the Auto Accompianment function supports your performance on the keyboard with various music styles such as rock 'n' roll