ok then, things went well ... I noticed in the packaging of the kit some components in surplus .. one of them was a 2SA733, which actually had a code different from all others except for a 733, mounted in Q1. I decided to replace Q1 with this surplus and, once again tested, I obtained a short in the 12V line, inserting the BA6110 in the socket, the voltage of 12 V rail drop down to 3 V!
From here the intuition that both transistors were banned or otherwise dysfunctional! Adapting a common 2N3906 PNP, I could see that my intuition was correct! Now everything is working right! Thank you all for the enormous help you gave me!
P. S. One last thing ... I'm not sure leaving this transistor in the circuit .. I think it definitely changes the sound a lot. What do you think? I could put in place of 2SA733P in Q1? I ardinato 2SA733Q, think can be a good substitute?
Again, thank you very much!