Formula xHD

About the Formula xHD

The Aqua Formula xHD is a high-end, Italian-made digital-to-analog converter using Aqua’s proprietary Optologic pure R2R ladder architecture. It is a fully balanced, modular, FPGA-based NOS DAC with a 1x oversampling factor and no digital filter. The xHD update introduced revised FPGA firmware and a galvanically isolated hybrid XMOS/FPGA USB interface, adding high-resolution PCM and native DSD playback. The later Formula xHD Rev. 2 version expanded USB support to native DSD512 and retained the modular input design, allowing one digital input section to be specified or upgraded. Available documentation is inconsistent between early xHD and later Rev. 2 specifications, particularly regarding maximum DSD rate, dimensions, and power consumption; the figures below distinguish the commonly reported Rev. 2 data where possible.