Does the Sony XA-300 work w/ that Sony head unit?
That image looks like my Sony CDX-H910UI and my system has the XA-300. It provides three selectable audio inputs, one is configured for a CD disc changer, like the CDX-T69 that is part of my system.
https://live.staticflickr.com/65535/48111080478_7c691a046f_c.jpg