wuzhi audio

This is Wuzhi HT21 3G circuit, I want to ask what is the marked part used for, please help me answer, thank you.

I have a beautiful JBL BAR 500 subwoofer (300watt, 10", 3ohm subwoofer that comes with JBL soundbars) that i want to convert from proprietary wireless to RCA input. The oem system is most likely (As the SW10 service manual states) a Syncomm IA9Q5 S83D comms module feeding a texas instruments...