Audio Research Reference 160M MkII Monoblock Power Amplifier

The Audio Research Reference 160M MkII is a reference vacuum-tube monoblock amplifier delivering 140 watts continuous from 20Hz–20kHz from four KT150 output tubes per chassis. Its fully balanced architecture combines switchable Ultralinear/Triode operation, proprietary automatic bias, output-tube monitoring and protection, 4/8/16-ohm output taps and Audio Research's signature GhostMeter™. Audio Research

Designed as a central model in Audio Research's current Reference amplifier range, the REF160M MkII brings substantial tube power, wide bandwidth and sophisticated tube management to demanding high-end loudspeaker systems. Audio Research

140-Watt Reference Monoblock

Each Reference 160M MkII produces 140 watts continuous from 20Hz to 20kHz. At 1kHz, Audio Research specifies approximately 1% THD at 140 watts, while distortion remains below 0.04% at 1 watt. Audio Research

As a true monoblock design, each loudspeaker receives its own complete amplifier chassis, power supply, output stage and output transformer.

KT150 Vacuum-Tube Output Stage

Each REF160M MkII uses:

4 × KT150 output tubes
6H30 tubes in the gain/driver circuitry

Audio Research combines the tube output stage with a refined topology using fewer, higher-quality components in the signal path. A four-layer circuit board provides the foundation for the amplifier's custom and premium components while helping maintain a short signal path. Audio Research

Ultralinear & Triode Operation

The Reference 160M MkII provides switchable Ultralinear and Triode operation, allowing the amplifier's output-stage behavior to be changed to suit the loudspeaker, system and listener.

Ultralinear mode provides the REF160M MkII's full rated output and greater available dynamic headroom, while Triode operation provides an alternative tube operating characteristic for systems where maximum power is not the primary requirement. Audio Research

Proprietary Automatic Bias

Audio Research's automatic bias system continuously maintains output-tube bias and compensates as the tubes age.

Importantly, the circuit isn't restricted to the factory-supplied KT150. Audio Research states that it can accommodate 6550, KT88 and KT120 tubes in addition to KT150s. Audio Research

This eliminates routine manual bias adjustment while making tube operation significantly easier to manage over the life of the amplifier.

High Energy Capacity Power Supply

The REF160M MkII incorporates Audio Research's High Energy Capacity Transformer and a substantial bulk-storage network engineered to supply high current during demanding musical transients. Audio Research

With each channel housed in a completely independent monoblock chassis, the left and right channels also have independent power supplies rather than sharing a common supply as they would in a stereo amplifier.

GhostMeter™

The distinctive GhostMeter™ combines a transparent front-panel display with a view of the amplifier's KT150 output tubes.

Rather than hiding the tubes behind a conventional meter, Audio Research integrates the power-output meter into the transparent front panel with etched markings and adjustable illumination. Audio Research

It has become one of the defining visual elements of Audio Research's contemporary Reference amplifiers.

4Ω, 8Ω & 16Ω Speaker Outputs

Dedicated output taps are provided for:

4 ohms
8 ohms
16 ohms

allowing the amplifier's output transformer to be matched appropriately to a broad range of high-end loudspeakers. Audio Research

Audio Research specifies output regulation of approximately 0.6dB from a 16-ohm load to open circuit, corresponding to a damping factor of approximately 14.

Wide-Bandwidth Design

The Reference 160M MkII offers unusually broad bandwidth for a high-powered vacuum-tube amplifier:

Frequency Response: 0.5Hz–110kHz (-3dB at 1W)
Power Bandwidth: 5Hz–70kHz (-3dB)
Slew Rate: 13V/µs
Rise Time: 2.0µs Audio Research

The amplifier uses 14dB of overall negative feedback.

Balanced & Single-Ended Connectivity

The REF160M MkII accommodates both balanced and single-ended systems.

Audio Research specifies:

Balanced input sensitivity: 2.4V RMS for rated output
Gain: 25.5dB into 8 ohms
Balanced input impedance: 200kΩ
Single-ended input impedance: 100kΩ

Output polarity is non-inverting, with XLR pin 2 positive. Audio Research

Tube Monitoring & Protection

The Reference 160M MkII combines automatic bias with output-tube monitoring and protection, addressing one of the primary ownership considerations associated with powerful tube amplifiers. Audio Research

The system continually maintains proper tube operation rather than requiring the owner to periodically measure and manually adjust bias.

Built for Reference Systems

At 56 lb per monoblock, the REF160M MkII is substantial without reaching the enormous scale of Audio Research's larger Reference amplifiers.

Each chassis measures:

17.25" W × 10" H × 18.5" D

with a depth of:

19.25" with handles extended. Audio Research

The amplifier is available in Natural/Silver or Black finishes.

Technical Specifications

Specifications follow Audio Research's current Reference 160M MkII product information. Audio Research

Audio Research Reference 160M MkII at The Grid HiFi

The Audio Research Reference 160M MkII combines 140 watts of tube power, four KT150 output tubes per monoblock, Ultralinear/Triode operation, automatic bias, wide-bandwidth circuitry and 4/8/16-ohm output taps in one of Audio Research's core Reference-series amplifiers.

The Grid HiFi can build the complete system around the REF160M MkII, including Audio Research preamplification, reference analog and digital sources, loudspeaker matching, cabling, power management and system setup.

Considering the Reference 160M MkII? Call The Grid HiFi at (713) 218-8120 to arrange a private audition and build the complete system around it.