[Ynze] found a basic design that works, and built from there. One of the interesting things about [Ynze’s] amp, as well as many of the Gainclones, is the fact that they use no circuit board.

This high-resolution audio amplifier delivers exceptional sound quality with a simple yet efficient circuit design. Engineered for powerful performance, it enhances audio output with clarity and ...

implementing as it does a complete simple op-amp with five transistors. Looking at the circuit diagram it follows the classic op-amp with a long-tailed pair of NPN transistors driving a PNP gain ...