Loud "plop" with libreelec and amp in car

Hello, I'm using libreelec 9.1.5 and rpi 3b as car-pc with m2-atx power supplier. The amplifier in the car is connected to analog output of the rpi and to the remote connector of m2atx. The remote connector is used to prevent the loud plop when car-pc starts by delaying the power supply of the amp, which is working.

But there is another loud noise between libreelec and kodi bootscreen which the remote connector cannot prevent since the amp already got power. I guess it's because of the audio device of rpi which is activated when kodi starts?

Will a hdmi audio extractor prevent this plop sound between boot screens? My amplifier has only rca connection, so I would need a extractor with rca output.

This topic can be closed now, since my hdmi-->vga converter cable has a 3,5mm output. Connecting the amplifier to the cable prevents the popping sound at start. So if anyone wants to get rid of the pop sound: DON'T USE THE ANALOG OUTPUT OF RPI!