Most simple way is a tool like midi-ox and a decent usb-midi interface to send the files. Jon Morgan's DX Manager is an excellent editor and libraria...

DX7 & SY77 line level: -10dBm at 600 ohms load or 0.1mW TX7 test 1: the volume will be at maximum about 250mV Formula dBm to volts: 0.775 x 10^(-10/...