From the Tisbury Audio website:
The Challenge Amp 1 is a high performance headphone amplifier, carefully engineered for precision and transparency. This powerful and versatile amp will drive virtually all headphones with 'reference grade' fidelity.
It features excellent specifications all round, including vanishingly low noise and distortion, ruler flat frequency response and near 0-ohm output impedance, all vital for a ensuring reference sound quality. The low gain mode and silent background is great for sensitive IEMs, while the high output power will easily drive more demanding headphones such as orthodynamics.
The amp is designed and made in England of predominantly British sourced parts. The wooden enclosures are hand made in Tisbury, Wiltshire from American black walnut and lined with copper shielding, while the 3mm aluminium chassis is brushed, anodised and CNC machined for a solid, high quality finish. The circuit board and most other components come from British suppliers and are assembled and tested in house by us, ensuring every amplifier meets our meticulous standards.