Really, everything has been said and written about this amplifier. Therefore no further explanations are needed.
About the build:
For this project we use selected standard components and again the chassis is not quite perfect out of the box. Similar to the 5F1, there is no pre-drilled hole for a separate PE connection. In order to achieve a compliant protective ground connection it is therefore advisable to add an additional hole to the chassis before starting the build process. Also one additional hole may be needed for the mounting of the Hammond output transformer.
Furthermore attention has to be paid to the strict observance of the grounding concept as shown in the layout plan, in order to avoid problems with hum and ground loops.
You can find the kit at the TT-Shop.
Care is necessary during construction! Even though this is a low-watt amp, the voltages used are potentially fatal. This amp is NOT a beginner's project!
A successful build requires that you can read (and understand!) a schematic diagram, you know how to use various measuring devices, and you have some experience working with voltages over 60V.