Sure there has to be single active component in an amp in order to get the gain to be called an AMPLIFIER. That's a simple amplifier as a single end tube amplifier. A single end vacuum tube Amp need a resistor or two and an output transformer. So I design a FET amp around the same simplicity of design. One audio grade MOSFET, a couple of resistors and capacitors and a heavy duty well filtered power supply. The schematic for the amplifier section is shown in Figure 1.