The amplifier website from Bert van der Kerk relates his voyage through the Williamson way of DIY, which during a period in the fifties of previous century, was a hole in the wall for early adopters.
It is proof that, if you own a pair of the extra ordinary output transformers, and if you know how to operate in the mortally dangerous world of high voltage, it still is possible in our times to relive the spine chilling experience of good sound.