Which "pin on Raspberry Pi" can tell DAC now playing DSD?

I used raspberry pi of P5 pin and DIY the cable directly into my DAC (like the northstar design DAC32 RJ45), and I want to use Volumio to play DSD music,but my DAC need a signal to tell that now I playing DSD music…
so, can anybody tell me how the Volumio control the DSD signal(In addition to the P5 pin? )
thanks a lot!!

What does the signal actually carry? Is it data, or simply a line pulled low/high to signal to the DAC what the stream is?

my dac need the signal to tell that now Rpi is playing DSD misic…
I want to know what’s pin(DSD) the volumio control…

thanks a lot!!