AUDIO RESEARCH REFERENCE TWO MKII

Pre owned. In good condition. Shows minor signs of wear on the edges, also visible in the photos. Supplied with remote control. Supplied without original packaging.

Stereo line preamplifier, the Audio Research Reference 2 MKII represents one of the American manufacturer's reference models from the early 2000s. An evolution of the original Reference Two, this version replaces the eight 6922 valves of the first series with 6H30P valves, aiming to improve linearity, reduce background noise and extend valve life.

The line stage features a fully balanced architecture designed to preserve signal transparency and provide an effective interface with different types of power amplifiers, both valve and solid-state. The gain stage employs four 6H30P valves in a balanced configuration, while the electronically regulated power supply uses two additional 6H30P valves, a 5AR4 rectifier and a 6L6GC dedicated to voltage regulation. The design does not include an integrated phono stage and is intended for use with line-level sources.

Connectivity includes balanced XLR and unbalanced RCA inputs, two main outputs and a Tape output, with independent source selection for listening and recording. Volume control is handled by a 125-step electronic attenuator, while the remote control provides access to the main functions, including input selection, channel balance, phase inversion and mute.

In terms of sound reproduction, the Reference 2 MKII is designed to deliver a wide, stable soundstage, a full-bodied yet natural midrange and effortless dynamics. For optimal performance, the manufacturer recommends a warm-up period of approximately 45 seconds before listening, while full stabilisation may take around one hour.

Discontinued and now available on the second-hand market, the Reference 2 MKII stands out for its fully balanced design, regulated valve power supply and suitability for high-end hi-fi systems. When purchasing a used unit, it is advisable to check the condition of the valves, any maintenance work previously carried out and the condition of the power supply components.

Technical specifications:

• Frequency response: 0.2 Hz – 60 kHz (+0/−3 dB) at rated output
• Total harmonic distortion: Less than 0.006% with balanced output at 2 V RMS
• Gain: Main output with SE or balanced input: 18 dB balanced; 12 dB single-ended; Tape output: 0 dB; Processor input: 0 dB balanced; Aux 1 input: 13 dB balanced
• Input impedance: 132 kΩ balanced; 66 kΩ single-ended
• Inputs: 8 inputs (Tape, Tuner, Phono, CD, Video, Aux 1, Aux 2, Processor); XLR and RCA connectors
• Output impedance: 400 Ω balanced; 200 Ω single-ended for the main outputs
• Outputs: 2 main outputs; 1 Tape output; XLR and RCA connectors
• Minimum output load: 20 kΩ
• Maximum load capacitance: 2000 pF
• Output polarity: Non-inverting
• Maximum input level: 14 V RMS balanced; 7 V RMS single-ended
• Rated output level: 2 V RMS balanced; 1 V RMS single-ended into a 200 kΩ balanced load
• Maximum output level: 40 V RMS balanced, with less than 0.5% distortion at 1 kHz
• Controls: 125-step gain control; balance; record selection; input selection; power on/off; SE/balanced input selection; phase inversion; mute/operate
• Power supply: Electronically regulated low- and high-voltage supplies; automatic muting during the 45-second warm-up period and in the event of a mains voltage drop; line regulation better than 0.01%
• Residual noise: 5.5 µV RMS, IHF-weighted, equivalent balanced input noise with gain control at minimum; 94 dB below a 2 V RMS output
• Valves: 4 × 6H30P dual triodes in the audio stage; 2 × 6H30P, 1 × 5AR4 and 1 × 6L6GC in the power supply
• Dimensions (W × H × D): 48 × 17.8 × 39.4 cm
• Weight: 14.2 kg