Boulder 1163 and 851 power amplifiers launch in Japan on November 21

Axis, Boulder's distributor in Japan, will launch the 1163 stereo and 851 mono power amplifiers on Saturday, November 21, 2026. The news was reported via Audio Review Blog. The prices are the distributor's recommended retail prices including tax in Japan: 6,930,000 yen for the 1163 and 5,060,000 yen per pair for the 851. The source does not include international pricing.

Which features stand out?

The 1163 replaces the 1161 stereo model in the 1100 series. PHILE WEB reports that the output stage uses the Class A bias method Smart Current, developed in the mono 1151. The method continuously adjusts the output stage via analog circuitry depending on the current flowing to the speaker and the frequency-dependent impedance. The aim is to reduce the heating and efficiency issues of Class A and lower crossover distortion. Boulder's official 1163 page does not mention Smart Current in its specifications section. The page only provides a link to the Class A Smart Current technical document.

The 851 is the first mono power amplifier in the 800 series to feature Class A output circuitry and Smart Current. It is the same size as the 812 DAC/preamp.

What are the technical specifications?

Boulder 1163

• Continuous output: 150 W (8/4/2 Ω); peak 200 W (8 Ω), 325 W (4 Ω), 550 W (2 Ω)
• Distortion: 0.002% (8 and 4 Ω, 150 W), 0.003% (2 Ω)
• Frequency response: 0.015 Hz–150 kHz (-3 dB); gain 26 dB
• Fully balanced circuitry input to output; 40 output transistors, 12 power capacitors
• 457 x 183 x 417 mm, 24.5 kg

Boulder 851

• Continuous output: 100 W (8 Ω), 200 W (4 Ω); peak 150 W (8 Ω), 250 W (4 Ω), 350 W (2 Ω)
• Distortion: 0.002%; frequency response 0.015 Hz–150 kHz (-3 dB); maximum gain 26 dB
• Single XLR balanced input; short-circuit current limiter, DC sensing, and thermal protection engaged at 70 °C
• 305 x 89 x 305 mm, 10 kg; maximum power consumption 550 W

Why does this matter?

The presentation of the same Class A output approach in both a large stereo and compact mono chassis demonstrates Boulder's next-generation power stage strategy. The difference in Smart Current between the official page and press communication reminds us that technical details for the 1163 need verification from the manufacturer.