costly +425V power supply enabled 15 Watt output power at no more than 0.1% distortion; this arrangement became standard for the Williamson amplifier and defined its physical layout. The complete prototype system, including the amplifier, the experimental magnetic pickup and a Goodmans full-range speaker in an acoustical labyrinth enclosure, has proven to Williamson that a low distortion, deep feedback amplifier, indeed, sounded superior to amplifiers without feedback. The difference was particularly audible with the best available shellac records, despite the physical limitations of this low-fidelity format. The prototypes impressed the Marconi management, who granted Williamson unlimited access to the company's test facilities and introduced him to the people from Decca Records. The latter provided Williamson with precious, exclusive test material - sample records of the experimental Decca ffrr system, the first true high fidelity medium in the United Kingdom. These records, which exceeded any preexisting media in sound quality, helped Williamson with fine-tuning his prototypes. He was certain that he was now firmly on the right track, but neither Marconi, nor its parent the General Electric Company were willing to invest in mass production of amplifiers for the civilian market. The design was not interesting to company lawyers either, because it did not contain anything patentable. Williamson merely put together well-known circuits and solutions. Publication In February 1946 Williamson left Marconi, moved to Edinburgh and joined Ferranti. A few months later a senior Marconi salesman, who sought new means of promoting the KT66 to general public, noticed Williamson's 1944 report about his amplifier prototypes, and sent it for publication to Wireless World. Chief editor H. F. Smith knew Williamson for his earlier contributions; he contacted the author directly and requested a detailed article written specifically for the DIY readers. Williamson promptly responded, but for unknown reasons the publication, originally slotted for 1946, was delayed until April–May 1947. While the paper was waiting for print, the magazine had published the new version of Cocking's Quality amplifier. Cocking, as the technical editor of Wireless World, certainly had precedence; according to Peter Stinson, he was sceptical about the Williamson amplifier, believing that his own design needed no further improvements. By 1947 British industry had already released two amplifiers of comparable sound quality. Harold Leak announced production of his Leak Point One in September 1945; later in the same year Peter Walker published the first sketch of his distributed-load output stage that would become