However, the photograph of the faceplate shows that the amp was equipped with both reverb and tremolo, which was never included on any Hilgen bass amplifier. Hilgen never designated an amp as a "Model S-9" or anything close to that, nor did it make an amplifier that was specifically designed for use by accordionists, as might be a reverb- and tremolo-equipped amplifier with a 15" speaker. The pilot light is one I have seen only on the Model R2024 Challenger, but its faceplate was black. The "Giulietti" logo on the front uses a construction and script design that was commonly employed by the Sano company in the early to mid-1960's, but was never used by Hilgen.
The Giulietti company was best known for producing ornate, high-end accordions. It apparently commissioned accordion amplifiers during the 1950's and 1960's, which amplifiers show design elements highly consistent with their having been made by Sano: