I made some changes to the layout that published mark the "Yerasov 5000V"
Replaced the 2 LEDs, with 2 BAT85 diodes.
Eliminated the Cap 22nF of Insulation1 who goes to ground.
Increased to 120nF Cap that goes to Pin 4.
I had a dramatic drop in volume, due to the compression and cropping, but the sound is really nice!
I would ask how I can fix to increase the volume.
Replacing the 50k with a 100k?
Replace 220nF going to Current3 a Link?
If possible before you make any other changes I would first opinion.