Thanks for taking the time to reply to my query ,it's much appreciated. I am aware of the sustain button and use it quite a lot. I am using the mzx500 as the work station / amplifier/recording device for my network of analog and digital synthesizers. They all have a "key hold" function which is useful when using more than two machines at the same time. Also useful when using arpeggios, background drones and noise effects. Anyway thanks again for your input . Much appreciated.