I have always enjoyed using Ham Radio Deluxe and DM780. I wanted an easy way to get audio line level output via the TRX2 AUX connector.
I placed one lead of a 0.1uf capacitor at the junction of IC10 pin 5 and capacitor C74 on the main board. A short wire is connected to the other lead of the capacitor.
A two pin shorting bar is soldered to the end of the wire. The jumpers on J5, the AUX selector, are removed and your shorting bar is placed on J5 pins 3 and 4, across the center two pins. [ : I : ] Now, Connect the Aux connector to the Microphone input of your computer.
Now you can enjoy DM780.
73's Robert KH2BR