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Power amplifiers stereo — Audio Research S-100
Description, images, technical data and specifications
Audio Research S-100
Image source - (c) Audio Research
The S-100 is a transistor stereo power amplifier from Audio Research and the most affordable model of its S-Series. It was joined by the larger S-200 as part of a broad release of new amplification products that the company announced in 2025. The S-Series comes from the company's dedicated solid-state engineering team, and both models are built at the Audio Research facility in Minnesota alongside its Reference tube amplifiers.
Key specs that matter
Output is 100 W per channel into 8 ohm and 200 W per channel into 4 ohm. Total harmonic distortion stays below 0.1% from 0.25 W up to rated output into 8 ohm at 1 kHz. Frequency response is within plus or minus 0.1 dB from 20 Hz to 20 kHz. Input impedance measures 100 kilohm whether the XLR or the RCA connection is used, and the balanced input reaches rated output with 1.4 V RMS. Gain is 26 dB, output noise is below 60 microvolts and the damping factor is 30 between 20 Hz and 1 kHz. Measured at the wall, the amplifier draws 0.25 W in standby, 48 W at idle and 475 W at rated output. The chassis measures about 483 mm wide, 178 mm high and 445 mm deep. Net weight is about 18.6 kg and the boxed weight is 28.6 kg.
Engineering and use context
Audio Research specifies a pure class AB design in a dual-mono layout, with two toroidal transformers feeding independent, fully balanced channels. That power supply arrangement is what lets the amplifier double its output into the lower load. A differential JFET input stage leads into bipolar transistor voltage and output stages. Audio Research chose bipolar output devices rather than MOSFETs for this series and explains the decision with its own listening priorities. A rear-panel selector switches between the balanced XLR and the single-ended RCA inputs. The case is machined from aluminium and anodized in black or silver, the heat sinks are custom machined, and no fasteners are visible from the front or the top.
Pairing
The moderate gain and balanced input sensitivity suit a line-level preamplifier with XLR outputs, while the RCA option covers sources and preamplifiers without balanced connections. The published ratings also cover low-impedance loudspeakers.
Alternatives
The Audio Research S-200 builds on the circuit topology of the S-100 and raises the rating to 200 W per channel into 8 ohm.
Key specs that matter
Output is 100 W per channel into 8 ohm and 200 W per channel into 4 ohm. Total harmonic distortion stays below 0.1% from 0.25 W up to rated output into 8 ohm at 1 kHz. Frequency response is within plus or minus 0.1 dB from 20 Hz to 20 kHz. Input impedance measures 100 kilohm whether the XLR or the RCA connection is used, and the balanced input reaches rated output with 1.4 V RMS. Gain is 26 dB, output noise is below 60 microvolts and the damping factor is 30 between 20 Hz and 1 kHz. Measured at the wall, the amplifier draws 0.25 W in standby, 48 W at idle and 475 W at rated output. The chassis measures about 483 mm wide, 178 mm high and 445 mm deep. Net weight is about 18.6 kg and the boxed weight is 28.6 kg.
Engineering and use context
Audio Research specifies a pure class AB design in a dual-mono layout, with two toroidal transformers feeding independent, fully balanced channels. That power supply arrangement is what lets the amplifier double its output into the lower load. A differential JFET input stage leads into bipolar transistor voltage and output stages. Audio Research chose bipolar output devices rather than MOSFETs for this series and explains the decision with its own listening priorities. A rear-panel selector switches between the balanced XLR and the single-ended RCA inputs. The case is machined from aluminium and anodized in black or silver, the heat sinks are custom machined, and no fasteners are visible from the front or the top.
Pairing
The moderate gain and balanced input sensitivity suit a line-level preamplifier with XLR outputs, while the RCA option covers sources and preamplifiers without balanced connections. The published ratings also cover low-impedance loudspeakers.
Alternatives
The Audio Research S-200 builds on the circuit topology of the S-100 and raises the rating to 200 W per channel into 8 ohm.
Specifications
Model name
S-100
Input sensitivity (mV)
N/A
Input impedance (balanced) (Ω)
100 000
Input impedance (single-ended) (Ω)
100 000
Output impedance (balanced) (Ω)
N/A
Output impedance (single-ended) (Ω)
N/A
Max current (A)
N/A
Output power (8Ω) (W)
100
Output power (4Ω) (W)
200
Gain (dBu)
N/A
Frequency response low +/- 3dB (Hz)
20
Frequency response high +/- 3dB (Hz)
20 000
Signal to Noise Ratio (dB)
N/A
Total Harmonic Distortion + Noise (0% global feedback) (%)
N/A
Total Harmonic Distortion + Noise (100% global feedback) (%)
N/A
Max power consumption (W)
475
Damping factor
N/A
Dimensions (mm)
483 × 171 × 432
Weight (kg)
19
Official link
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