Musical Fidelity - V90-HPA Headphone Amp The design aim of the V90HPA was to offer neutrality and faithfulness to the original signal, delivered as the artist intended it to be right to your ears. Every aspect of the design was conceived to achieve this end. The V90HPA offers a high input impedance and low output impedance and will easily drive the vast majority of headphones (from 10 ohms to 600 ohms). It has very low distortion typically less than 0.005% across the audio band. It also delivers an outstanding signal to noise ratio of better than 109 dB (A' weighted). The frequency response is 20 Hz to 80 kHz (1dB). The V90HPA's combination of very low distortion, extremely low noise, flat frequency response and low output impedance gives a smooth effortless sound quality that belies its modest price. The 24 bit 96 kHz asynchronous reclocking USB input has excellent technical performance. It accepts 16 to 24 bits with any standard sample rate up to 96 kHz.