Firest, you need cut-off oroginal cable like this. This make mods easier.
Open the connector. See following photo.
You will see "MADE IN CHINA" marking on bottom side of the connector. There are 6 small thi holes.
Put in some thin object, like screw drivers.Thi will release internal plastic latches.
Then you will see this.
Next, you will need to open "can". This is easy to open. Take off the cover part.
You will see one chip marked "MX". That is DAC(Digital to Analog Converter).