I already checked that yesterday
I wasable to replicate it by unplugging the turett harness and plugging a LED in the greenand white ports, so it's from the soundcircuit as you said (has nothing to do with theturett wiring, interference from the LED witing and so on)
So, as long as the LED circuit is closed, the pulse current sent to it in order to flash the leds will somehowcreate interference tothe speaker.