Here is the original prototype amplifier from which the published distortion traces were taken. It was built on a piece of veroboard using whatever components I had available at the time. No 'special audio grade' components or OFC wiring were used in the construction of this amplifier.
This is the amplifier I use myself at present, (it is the 85watt mosfet amplifier I gave the circuit diagram for somewhere), and it has been in regular use for almost 20 years. The toroidal transformer is 300VA and the big smoothing capacitors are each 27,000 uF and rated at 28 amps. Although the heatsink is fairly small the thermal cutout has never operated in normal use. Only one circuit board is visible, one is mounted under the other. This seems a good layout to use, both inputs being at the opposite end of the case to the transformer, and all amplifier earth leads can be taken to a single point with very short wires.
Here is an early experimental version of my latest design. The layout is a bit untidy because it was redesigned several times during construction. The final version will have a neater board layout. Five transistors are bolted to the heatsink bracket, along with a solid-state thermal detector.