Hi Skipjack K8. MIDI stands for Musical Instrument Digital Interface. It's a system that allowes electronic instruments to be controled by external devices, such as a computer or another electronic instrument. More precicely MIDI is a series of instructions that the makers of instruments have agreed will tell those devices what note to play at what volume and with what sound. So if you want to get your Accordion to play piano sounds you need it to generate MIDI massages when you play a note. You then need an electronic instrument(keyboard or Sound module) to interprit the message and tern it into a piano sound. The difficult bit is getting the MIDI messages from your Accordion, if you could find a way of doing that then all you have to do is plug yourself into a sound module and of you go. To find out more about MIDI just enter it in your search engine; ther's lots out there. All the best PP