The Darlings are a family of simple amplifiers based on a nice coke bottle triode - the 1626.
The idea of a supersimple lowpower (0,75W) SET seemed attractive but adding another trioded SE amp to my project plans was .... too much. Then I saw this idea on Matrix amplifiers which is a SE-amp using a PP-transformer. Er .. well two. The two triodes are connected to the first amp as normal for a PP-amp. On the secondary two outputs are made for left and right channel. As the OP signals are the difference signal of the input signals, the second transformer is used to form the sum of the input signals which is fed to the output cancelling the negative elements and thus regenerating the original two signals.
But then again, trying to stuff everything into the Swiss cheeze chassis seemed as a crazy task so I reverted to the first idea - the Original Darling. For chassis I am using a wooden box, once containing a set of dosimeters (for detecting radiatiation). Box painted greed indicating its military genes...
The amp part is housed in the lid which barely closes - the the 1626 been 2mm wider - no chance.
The PSU is in the box. All is according to the original schematic but using cheap components from a local Swedish shop.