Proxima A is the evolution of the design that started with the D₂O Amplifier. Start with a D₂O. Replace 6L6GC with 6V6GT output tubes, scaling down size, weight, and output power. Replace output power switch with a continuously variable no-tone-suck master volume so you can crank up the gain with or without hearing damage. Add a front-end boost circuit with three switchable modes: bypass (OG D₂O preamp), medium gain, and high gain, each with it's own voicing. Fundamentally, Proxima A is a much more versatile amp in terms of colors of gain available at arbitrary volumes, but still retaining the core sound and identity established with the D₂O. It also looks pretty great in its new color scheme.