About the Reference Phono 10
The Audio Research Reference Phono 10 is a fully balanced, pure Class A tube phono preamplifier with a true dual-mono layout. The left and right channels have separate signal paths and power supplies, including dedicated high- and low-voltage transformers, vacuum-tube regulation, and dual umbilical connections between the power supply and audio chassis. Its low-gain section uses eight 6H30 tubes, while high gain is provided by low-noise FET circuitry rather than a step-up transformer. The unit provides two inputs with selectable low or high gain, loading options of 47kΩ, 1kΩ, 500Ω, 200Ω, 100Ω, 50Ω, and custom loading, plus selectable RIAA, early Columbia, and Decca equalization curves. RCA inputs can be used in the balanced signal path without an inverter. Published specifications include 51dB/74dB balanced gain, 45dB/68dB single-ended gain, 200Ω single-ended and 400Ω balanced output impedance, and a frequency response of ±0.2dB from 10Hz to 60kHz relative to RIAA.