He can use even smaller transformer.
65 percent of transformer power will be transformed or obtained as audio..... people can even use a 200 watts transformer if they do not want power.... they will have 60 per channel and will be playing with their amplifier....this way the guy can even produce short circuits in the output wires to have fun watching audio sparks without burn 10 huge power transistors.
Chart shows power to each case, or to several distortion levels...having a 200 watts transformer, so, playing 60 watts each channel, you will have very low distortion too.
Select your transformer to match your speaker coil, to avoid to have speakers destroyed...so, people do not need to use full power that can reach more than kilowatt if they have 200 watts speaker.
This way, the selection of transformer power can match your needs, can save some money related the transformer cost and also you can reduce the cost to output transistors if you will not use big power.
This amplifier, unlike many others, can operate from 4.5 plus 4.5 volts till 70 plus 70 volts...and the power in the output terminals can go from a couple of watts to more than a kilowatt...a very flexible unit you have.
Enjoy folks...i have worked as an animal to make a nice thing to your enjoyment.... it is time to enjoy folks!
Very few amplifiers in this world can match or beat this unit you are building...and the price of these units can go above 10 thousand dollars.... and this not only because audio quality, but also because (mainly) of power, as amplifiers are sold with power as a reference to the price.
regards,
Carlos