What The function of this parts

[Rembulan]

Hello All,

I try to understand how this classD amp work but I can not understand what exactly the function of this parts with the surround parts. maybe some body can help me to understand.
any information is really appreciate

 

[greenocean]

T14 or T15 feed the diode side of optocoupler U25 , but what is the other side of U25 connected to?

 

[Rembulan]

T14 or T15 feed the diode side of optocoupler U25 , but what is the other side of U25 connected to?

Good Question and I don't know I only found that part. when I try to found variation for ClassD output