Mostlyaudio’s article about building the AudioNote Kit1 PQ Signature Edition SET amplifier. “This kit will build a very high quality Single-Ended, Class A, directly heated triode amplifier. The amplifier will support a single line source (unless a pre-amp is used that will support more sources) as it incorporates a volume control. It has a class A output of 8watts per channel. Don’t be put off by this seemingly low wattage as it is every bit as loud, position for position, as my my old 40W Linn solid state amplifier was through the same speakers. It also has an input impedance of around 100K which is more than ample for a huge range of source components.” Link.