we are not interested in PA systems here.......you can bring it somehwere else.......many of the users here use amps in the home setting, not in the streets...... 
have you read professor Leach's writings? did you understand?
i know what your problem is, either you do not understand schematics or you have problem understanding english.... 
if you say you are not an engineer, i will understand.....but if you say you are, then shame on you....
thats your way of escape. home audio and PA system are working in the same principle. the differences between the two are the power capability, damping factor and sound quality but still they are amps...amps...amps...Home audio is more on sound quality and PA are more on power and DF. and your superamp is not for home settings we can consider it as PA systems. as my amp is only 80w but too loud inside my home how much more a several 100w amps...
on the other hand PA system can also be use inside the home with minimal volume or home audio can also be use outside the house or street for party time...
so is there any difference between home audio and PA systems? i don't know any differences between the two.
The major difference between the two is the addition of transistors Q22 through Q31. Q22 is connected as a common base stage at the output of Q12. The two transistors form a cascode stage. The base of Q22 connects to the junction of R52 and R54. These two resistors are equal and are connected as a voltage divider between the loudspeaker output and the positive rail.
so where is the darlington you said...
wew i can't understand the way you understand...lolthe leach superamp made use of bert locanti's Tripple darlington output configuration....the basis for many of today's power amps....
...baka magkaiba tayo ng darlington configuration...lol
this is an 8ohm, 250watts power amp, although it can handle 4 ohms and occasionally 2ohms, i did not dare use it for speakers other than 8 ohms.....imho it is foolish to subject amps to low impedances....
my amp driving 4 ohms so you mean i'm foolish or your amp is weak. i understood what you said because DIY amps has no protection features so you does it as your way of escape in order not to harm or damage your amp from its weakness.
ano naman problema mo sya profession natin. kung may mali ako di sabihin mo. this is part of discussion and let us understand this by principles. di ka naman siguro insecure.
...at saka pede ba walang personalan..paliwanag mo lang anong ang mali wag naman yung attacking personal limitations. di naman ako katulad mo kagaling...lol
