The Audio Research S-100 marks a return to solid-state amplification for Audio Research, using the company’s long-established approach to circuit design, component selection and extensive listening evaluation. It is a 100-watt-per-channel Class A/B stereo amplifier built around a dual-mono architecture, with separate toroidal transformers for each channel and a fully balanced signal path.
The S-100 uses a differential JFET input stage followed by a voltage amplifier and bipolar-transistor Class A/B output stage. Audio Research chose bipolar output devices rather than MOSFETs, with the goal of combining low-level detail and transparency with strong current delivery and dynamic performance.
 
With 100 watts per channel into 8 ohms and 200 watts per channel into 4 ohms, the S-100 is designed to maintain its composure with speakers that demand additional current. The dual toroidal transformers and generous power supply allow the amplifier to double its rated output as impedance is reduced.
 
The signal path is fully balanced from input to output. Both balanced XLR and single-ended RCA connections are provided, with the input configuration selectable from the rear panel. This allows the S-100 to work equally well in fully balanced systems or with conventional RCA-based preamplifiers.
 
The amplifier is housed in a machined aluminum chassis with custom-machined heatsinks and a clean, contemporary interpretation of Audio Research's traditional design language. The front and top surfaces are free of visible fasteners, while the amplifier is available in black or silver anodized finishes.
Audio Research builds the S-100 in Minnesota, where each amplifier is bench tested and evaluated by ear before leaving the factory.
 
Key Features
• 100 watts per channel into 8 ohms
• 200 watts per channel into 4 ohms
• Class A/B solid-state design
• Dual-mono architecture
• Dual toroidal power transformers
• Fully balanced stereo circuit
• Differential JFET input stage
• Bipolar transistor voltage amplifier and output stages
• Balanced XLR and single-ended RCA inputs
• Rear-panel selectable balanced/single-ended operation
• Machined aluminum chassis
• Custom-machined heatsinks
• Black or silver anodized finish
• Made in Minnesota