The amplifier works well yes as I specified above talking about the preamplifier they have no sketch either. I saw two OS and CS jumpers on the board which is the most suitable for the amplifier in question and a preamplifier with high low averages and volume. However, the amplifier works without jumpers. And you can tell me where to put 2 resistors of 200 ohms (196 per picture) left. The sketch was diverse at least for me who is used to it. Please wait for an answer by e-mail.
Arrived late due to COVID limitations, otherwise good.