Audio Research D-80 – Tube Two-Channel Power Amplifier

The well-known manufacturer of tube audio equipment, Audio Research, has introduced a new stereo power amplifier, the Audio Research D-80, in the Reference series, combining pentode operation, automatic bias adjustment and balanced signal transmission with an output power of 70 W per channel.

The Audio Research D-80 power amplifier is built with fully balanced circuitry, where the signal path remains balanced from the input to the speaker terminals. Operation of the output tubes in pentode mode provides higher output power while, according to the designers, maintaining a controlled and structured sound. Audio Research deliberately omitted switchable operating modes of the output stage and complex additional features in order to focus on stability and sonic consistency.

The resemblance of the new product to the Audio Research Reference 80S amplifier is particularly noticeable in the power supply and output stage design, although the D-80 is built in a more economical chassis. Accordingly, the price of the amplifier is also lower.

The Audio Research D-80 power amplifier is entirely manufactured in the USA. Each unit undergoes several cycles of testing and is individually verified in the manufacturer’s reference system. According to the developers, this thorough process guarantees that the stated specifications are achieved not only on paper but consistently confirmed in practice.

The output stage of each channel uses a pair of matched KT150 output tubes, supplemented by two 6H30 tubes in the driver and gain stages. The KT150 tubes provide stable power delivery even when driving complex loads. The rated output power of 70 W per channel is available across the meaningful frequency range (from 7 Hz to 68 kHz at -3 dB), with additional dynamic headroom for short-term peak loads. In practice, this solution allows operation with a wide range of high-quality loudspeakers without pushing the amplifier to its limits.

The Audio Research D-80 power amplifier is specifically designed for use with balanced preamplifiers and is equipped exclusively with XLR inputs. This approach minimizes interference and is compatible with modern High End preamplifiers featuring fully balanced connections. Separate outputs are provided for speakers with 4 Ohm, 8 Ohm and 16 Ohm impedance, allowing precise matching with different loads.

An important feature of the Audio Research D-80 amplifier is the continuously operating automatic bias adjustment. It monitors the operating point of the output tubes in real time and automatically compensates for changes caused by mains voltage fluctuations or tube aging. As a result, manual adjustment is not required and the amplifier always operates under optimal conditions. This aspect emphasizes the practical goal of the D-80: making classic tube technology convenient without additional maintenance.

The Audio Research D-80 stereo power amplifier is offered in two finishes – black and silver – and is already available in Europe at a recommended retail price of 15,500 euros.