Boulder Amplifiers 851

The Boulder Amplifiers 851 Mono Power Amplifier represents the next evolution in high-fidelity amplification, bringing the revered performance and engineering pedigree of the acclaimed 861 Stereo Power Amplifier into a dedicated monoblock format. Designed for audiophiles and professional installations that demand pure, uncompressed power, the 851 Mono delivers 100 watts of continuous output into 8 ohms with phenomenal control, transparency, and musical authority.

At its core, the 851 Mono Power amp improves upon the proven amplifier design of the original 861 Stereo Power Amp, including ultra-wide bandwidth response, extremely low distortion, and robust protection systems. By simplifying the signal path, dedicating each chassis to a single channel, and implementing the ground-breaking Smart Current Technology Output Stage; Boulder’s engineers have extracted every bit of resolution and dynamic nuance from the design while enhancing headroom and channel separation.

The first amplifier in the 800 Series to implement the all new Smart Current Output stage.

Along with assembly and testing, every circuit board and piece of metalwork is produced in-house at Boulder's dedicated facility for unparalleled quality assurance

Boulder's traditional in-house 0.25" (6 mm) thumbscrew binding posts for secure speaker cable connections and optimal sound quality

Space saving design is the same footprint (width and depth) as the 812 DAC Preamplifier, and 808 Phono Preamplifier

The only Class-A amplifier in the 800 Series.

100 W Continuous Power into 8-Ohms

Sophisticated protection circuitry to prevent any potential damage to your system

Software updates to the internal control and housekeeping systems available as needed with automated online downloads or manual USB port installation

150 W Peak Power into 8 Ohms