Thank you both. My starting point was something like Mark's estimate which does not sound promising for a max 45V V_CEO component. I must admit, WD, that I do not understand what 'assume the constant current source gets in the way' means as the collector of Q2 connects directly to the positive rail and its emitter must stay somewhere around to zero, otherwise Q2 would not conduct at all.
2N5551 seems to be compatible with the ZTX450 pinout (EBC), KSC1845 is different (ECB).
Btw, is there a simulation / measurement / educated guess about the current draw of the small signal parts of the amplifier? I found 8.3mA for Q5 and Q6 earlier in the discussion but nothing about the currents of Q1 and Q2 (which might be trivial to experts but I am none of those).
2N5551 seems to be compatible with the ZTX450 pinout (EBC), KSC1845 is different (ECB).
Btw, is there a simulation / measurement / educated guess about the current draw of the small signal parts of the amplifier? I found 8.3mA for Q5 and Q6 earlier in the discussion but nothing about the currents of Q1 and Q2 (which might be trivial to experts but I am none of those).
I have only raised the gain, and I adjusted R3 down, from 1k to 475k and went from 27 up to 33 gain. I would imagine you could just go the other way to 1.5k (~22 gain) or even 2k (lower to ~15 gain) not sure the exact rate it will lower your gain?
Regarding the transformer, if that is unloaded VAC, then you will be fine by the time you account for 3-4v of loss you will end up at 50-53Vdc - I run mine with 52Vdc and haven't had any issue in a year.
I don't need
You need it, for amp you want to make
There are myriad of appropriate books on subject, and your understanding of processes involved will be much higher than based on just few replies on forum
One major fact - efficiency