Boulder Amplifiers was founded in Boulder, Colorado in 1984 with a single governing principle: that the path to exceptional audio performance is not found in clever circuit shortcuts, but in the relentless elimination of every source of distortion and noise, regardless of cost or complexity. Forty years later, that principle remains unchanged. Boulder builds a small number of amplifiers each year — each one assembled by hand, measured individually, and shipped only when it meets standards that most amplifier designers would consider impossible to achieve in production.

ENGINEERING PHILOSOPHY

A Boulder amplifier is not designed around a price point. It is designed around a performance target, and then priced accordingly. The circuit topologies Boulder employs — including their proprietary 983 gain block, used across the reference product line — are evolved from decades of refinement rather than reinvented each product cycle. The result is electronics of extraordinary stability, vanishingly low distortion, and a sonic character that is best described as the complete absence of character: no warmth added, no edge softened, no signature imposed. Boulder amplifiers reveal what your source material and your speakers are actually doing — and they drive any load, at any listening level, without strain or compromise.

WHY THE AUDIO TAILOR CARRIES BOULDER AMPLIFIERS

We carry Boulder because our most serious clients eventually reach a point where they need amplification thatwill not be the limiting factor in their system — today, or in fifteen years. Boulder is that amplification. It is, in the truest sense, a final purchase.

861 Stereo Power Amplifier

There is a solution for those in smaller living spaces, for those that have efficient systems, or for those who like the 866 Integrated sonically but prefer separates. The 861 Stereo Power Amplifier checks all these boxes. The 861 being the newest expansion of the 800 series is the same exact size as the 812 DAC Preamplifier it makes for an attractive combo both visually and audibly. All the boards and chassis are still made in Boulder’s dedicated facility in Colorado. You get the high performance, the expertise and craftsmanship in a manageable package.

The 861 is Boulders first amplifier in its size and it punches well above its weight class. Don’t believe us? You should really listen for yourself.

Features:

• 75W peak power per channel into 8 ohms, 110W peak power into 4 ohms, 200W peak power into 2 ohms
• New protection circuitry enables the 861 to deliver greater current at maximum output without fear of damage to the amplifier's electronics
• Space saving design is the same footprint (width and depth) as the 812 DAC Preamplifier
• In-house manufacturing efficiency improvements have made the 861 an incredible value in comparison to previous amplifiers
• Smaller carton packaging means easier transportation, unpacking, and installation
• 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 are included for secure speaker cable connections and optimal sound quality
• IP control, and networked HTML page
• Software updates to the internal control and housekeeping systems available as needed with automated online downloads or manual USB port installation

Specifications:

• CONTINUOUS POWER, 8 OHMS: 50W
• PEAK POWER, 8 OHMS: 75W
• CONTINUOUS POWER, 4 OHMS: 90W
• PEAK POWER, 4 OHMS: 110W
• PEAK POWER, 2 OHMS: 200W
• BALANCED ANALOG INPUTS: 1 pair balanced via 3-pin XLR
• OUTPUTS: .25" (6mm) Binding posts
• DISTORTION, THD: 0.01%
• EQUIVALENT INPUT NOISE (EIN), 20 KHZ: 2.6 μV
• INPUT IMPEDANCE: 100kΩ Balanced
• FREQUENCY RESPONSE, 20 HZ TO 20 KHZ: +0.00, -0.04 dB
• FREQUENCY RESPONSE, -3 DB: 0.015 Hz, 150 kHz
• MAXIMUM ANALOG GAIN: 26 dB
• POWER REQUIREMENTS: 100V, 120V, 240V, 50-60 Hz
• POWER CONSUMPTION: 550W Maximum
• DIMENSIONS: 12"x12"x3.5"
• WEIGHT: 22 lbs