Audio Research S-100 Stereo Power Amplifier Expands the Brand’s Solid-State Line
By HiFi Editorial24 February 2026
Key Highlights
Audio Research expands beyond tube designs with the S-100 stereo power amplifier, a solid-state Class A/B model targeting demanding high-end stereo systems.
The dual-mono architecture uses two independent toroidal transformers and fully balanced circuitry, minimizing crosstalk while ensuring stable power delivery under dynamic loads.
Rated at 100 W per channel into 8 ohms and doubling to 200 W into 4 ohms, the S-100 offers high current capability for low-impedance speakers.
What makes the S‑100 particularly interesting is not the fact that Audio Research builds a transistor amplifier, but how it does so. The decision to rely on bipolar output devices rather than MOSFETs places the S‑100 firmly in the camp of amplifiers prioritizing linear current behavior and precise control over complex loads. In audiophile circles, this choice is often associated with tighter bass articulation and a more explicit rendering of microdynamics, especially when loudspeakers present reactive impedance curves. Combined with a fully balanced signal path and a deliberately conservative gain structure, the S‑100 appears engineered to behave as a transparent current source rather than a “voiced” power amp, even though Audio Research traditionally emphasizes musical expressiveness as much as measurement discipline.
