Benchmark AHB2 Power Amplifier

Sale price$3,499.00

Color: Black

Benchmark AHB2 - The Quietest, Cleanest Audio Amplifier on the Planet

From the first watt to the last watt, no audio power amplifier offers lower noise or lower distortion than the Benchmark AHB2.Benchmark has raised the bar by introducing a new and revolutionary amplifier!

“I measured less distortion and noise in the AHB2 than in any other of the many power amps I've measured over the years.”

-Bascom King, BHK Labs

“If ever there were a giant-killer of an amp, this is it.”

"It is one of the -- if not the -- quietest, most resolving amps I've heard. Time and again, without ever having intended to, I wound up hours deep in listening to the fringes of my music collection, thanks to the AHB2’s reference-level transparency and obscene athleticism."

- Hans Wetzel, SoundStage!

"Benchmark Media Systems' AHB2 is an extraordinary amplifier. Not only does its performance lie at the limits of what is possible for me to reliably test, it packs high power into a very small package, especially when used in bridged-mono mode. It is truly a high-resolution amplifier."

- John Atkinson, Stereophile

True High-Resolution Performance 

The AHB2 is the ideal match to the performance limits of High-Resolution-Audio (HRA) formats. Benchmark's AHB2 power amplifier delivers musical details without introducing the masking effects of amplifier noise and distortion. The dynamic range of the AHB2 is 132 dB, making it 10 to 30 dB quieter than some of the very best reference-quality power amplifiers.

The frequency response of the AHB2 extends beyond 200 kHz. With the AHB2, you will discover previously overlooked nuances, dynamics, and detail in your favorite recordings and experience the full potential of the latest high-resolution 24-bit PCM and 1-bit DSD audio formats.

Experience the Emotion

The musical details and emotion captured on today's finest High-Resolution-Audio recordings can only be fully appreciated when every component in the signal chain is capable of true high-resolution performance. Power amplifiers are a weak link in most audio systems. Most power amplifiers are well matched to the limitations of the CD format, but they fall well short of the capabilities of high-resolution formats. In contrast, the revolutionary AHB2 was specifically designed to deliver true high-resolution performance.

"Best Stereo Amplifier of 2017 ... masterfully detailed and transparent with spot-on tonality and some serious punch."

- Ben Shyman, Home Theater Review


D/A conversion technology has outpaced the development of new power amplifiers. This means that the power amplifier has become a limiting factor in many audio systems. For example, the noise and distortion produced by the Benchmark DAC3 D/A converter is 20 to 30 dB lower than that produced by most high-quality power amplifiers. Until now, this meant that the DAC3 could not be fully appreciated. Benchmark set out to solve this problem by creating an amplifier that matches the performance of the DAC3.


We had to look beyond existing amplifier technologies and explore some new and radical solutions. In our search, we learned of two new patents on a new amplifier technology from THX. This was exactly the technology we needed to build our new amplifier.

The AHB2 uses the new and revolutionary THX-patented AAA™ technology to virtually eliminate all forms of distortion. This technology uses feed-forward error correction to eliminate the distortion that is normally produced by the output stage.  No other audio amplifier comes close to delivering the clean, quiet, and robust power of the AHB2.

Difficult Speaker Loads are Handled With Ease

Many loudspeakers have frequencies at which their impedance drops to levels that are much lower than the "nominal" impedance. The AHB2 drives difficult phase angles and low impedances with ease. Stereo loads as low as 1.4 Ohms can be cleanly driven to full output levels. Most power amplifiers produce higher levels of distortion when the load impedance decreases. In contrast, the feed-forward error correction system in the AHB2 keeps the output clean when driving difficult loads. The AHB2 produces almost no measurable distortion at any rated load condition.

In our quest to build the ultimate amplifier, we also focused on frequency response, output noise, drive current, damping factor, and reliability. The result is an amplifier that stands head and shoulders above the competition.


This Benchmark product was designed, assembled, and tested in the USA using USA and imported components. Most major components are made in USA.

Sonic Purity that Surpasses Class A!

The AHB2 is a linear amplifier that surpasses the sonic purity of all class-A amplifiers. No amplifier delivers lower noise or lower distortion. The small, passively cooled chassis, cleanly delivers 480 Watts bridged mono into 6 Ohms, with additional reserves for driving difficult speaker loads. Unlike power-hungry class-A amplifiers, the AHB2 achieves a power efficiency that rivals that of a Class D (switching) power amplifier.

Difficult Speaker Loads are Handled With Ease

Many loudspeakers have frequencies at which their impedance drops to levels that are much lower than the "nominal" impedance. The AHB2 drives difficult phase angles and low impedances with ease. Stereo loads as low as 1.4 Ohms can be cleanly driven to full output levels. Most power amplifiers produce higher levels of distortion when the load impedance decreases. In contrast, the feed-forward error correction system in the AHB2 keeps the output clean when driving difficult loads. The AHB2 produces almost no measurable distortion at any rated load condition.

High Damping Factor

The AHB2 has a high damping factor that augments its extended low-end to deliver solid, well-controlled bass. This high damping factor also keeps the frequency response absolutely flat while driving speakers with large frequency-dependent impedance variations.

High Output Current

The AHB2 can deliver up to 29 A peak to each channel simultaneously. This robust drive current easily handles some of the most demanding loudspeakers. The AHB2 has tightly regulated power supplies that keep the output clean while delivering high current.

Distortion is Below Audibility

The AHB2 will never produce audible distortion. In most playback systems, the distortion produced by the AHB2 will never even reach the 0 dB SPL threshold of hearing. This means that the distortion could not be heard, even if it could be played while the music was muted.

The AHB2 allows you to escape the distortion limitations of classic amplifier topologies and enter the world of high-resolution audio playback.

"I very much enjoyed my time evaluating the Benchmark AHB2 amplifier and can heartily recommend it to those seeking one of the lowest distortion and lowest noise amplifiers on the planet—one that is very musically transparent and easy on the ears to boot."

- Frank Alles, Stereo Times

Extreme Performance Often Requires a Radical Approach

The AHB2 amplifier is radically different than traditional audio amplifiers. Two new THX-patented feed-forward error-correction technologies eliminate most sources of distortion. An unconventional power supply maintains tight regulation and low ripple while minimizing magnetic fields. A low-gain topology optimizes the gain staging between the D/A converter and the power amplifier while minimizing noise. Sophisticated shielding and star-quad signal distribution provide outstanding immunity to interference. A unique output stage incorporates class-H tracking power supply rails to improve efficiency. The result is that the cool-running AHB2 has a signal to noise ratio of 132 dB while distortion is at or below the measurement limits of the finest test equipment.

See John Siau's application note: "A Radical Approach to Power Amplification" for more details.

Introducing THX Achromatic Audio Amplifier Technology™

The AHB2 is the only amplifier that leverages the patented THX-AAA Technology™. This patented system reduces distortion to vanishingly low levels while enabling several power-saving techniques.

"The Benchmark AHB2 is a powerful and efficient amplifier with prodigious low levels of noise and distortion. The fact that it is also very musical and non-fatiguing, courtesy of THX’s patented AAA Technology™, is the icing on the cake. Benchmark Media and THX have a lot to be proud of for the development and implementation of the new technology the AHB2 represents."

- Frank Alles, Stereo Times

Bipolar Class-AB Output Stage

The AHB2 has a bipolar class-AB output stage that delivers high output current and low noise. The THX-AAA Technology™ provides accurate cancellation of zero-crossing errors, exceeding the performance of the best class-A amplifier.

Feed-Forward Error Correction

Traditional class-AB amplifiers generate crossover distortion every time the push-pull output stage crosses 0 volts. This crossover distortion can be especially problematic at low playback levels.

In contrast, class-A amplifiers eliminate crossover distortion by keeping all output devices turned on at all times. This brute-force class-A approach solves the crossover distortion problem but it consumes lots of power while delivering very little to the speakers. The wasted power produces heat which must be dissipated into the listening space.

Class-A amplifiers eliminate crossover distortion but they suffer from high power consumption, poor damping, and limited output power. The AHB2 is the first amplifier to virtually eliminate crossover distortion without incurring the undesirable side effects of class-A amplification.

Continuous Average Output Power

< 0.0003 % THD+N at full rated power, 20 Hz to 20 kHz

  • 100 Watts per channel into 8 Ohms, both channels driven
  • 130 Watts per channel into 6 Ohms, both channels driven
  • 190 Watts per channel into 4 Ohms, both channels driven
  • 240 Watts per channel into 3 Ohms, both channels driven
  • 200 Watts into 16 Ohms, bridged mono
  • 380 Watts into 8 Ohms, bridged mono
  • 480 Watts into 6 Ohms, bridged mono

All speakers have variations in input impedance. Select loads based on nominal impedances not minimum impedances. The AHB2 is stable into all loads. The AHB2 is conservatively rated at an output level where THD+N is < 0.0003 % instead of the more typical 1% THD+N. Power at 1% THD will be higher.

Output Voltage Into Various Load Impedances

< 0.0003 % THD+N at the following output voltages and load impedances, 20 Hz to 20 kHz

  • 29.03 dBV, 31.25 dBu, 28.28 Vrms into 8 Ohms, both channels driven
  • 28.92 dBV, 31.14 dBu, 27.93 Vrms into 6 Ohms, both channels driven
  • 28.81 dBV, 31.03 dBu, 27.57 Vrms into 4 Ohms, both channels driven
  • 28.57 dBV, 30.79 dBu, 26.83 Vrms into 3 Ohms, both channels driven
  • 27.14 dBV, 29.36 dBu, 22.76 Vrms into 2 Ohms, both channels driven
  • 35.05 dBV, 37.27 dBu, 56.57 Vrms into 16 Ohms, bridged mono
  • 34.83 dBV, 37.05 dBu, 55.14 Vrms into 8 Ohms, bridged mono
  • 34.59 dBV, 36.81 dBu, 53.67 Vrms into 6 Ohms, bridged mono
  • 33.16 dBV, 35.38 dBu, 45.52 Vrms into 4 Ohms, bridged mono

Use dBV to calculate the peak SPL from your speaker/amplifier combination. Use the following formula: Amplifier output voltage in dBV + speaker sensitivity at 2.83V - 9 dB. Example: (29.03 dBV at 8 Ohms) + (90 dB SPL @ 2.83V 1m) - 9 dB = 110 dB SPL at 1 meter

SNR & Dynamic Range

Rated output relative to output noise, inputs shorted

  • 132 dB A-weighted, Stereo Mode
  • 135 dB A-weighted, Mono Mode
  • 130 dB Unweighted, 20 Hz to 20 kHz, Stereo Mode
  • 133 dB Unweighted, 20 Hz to 20 kHz, Mono Mode

Noise Voltage

Output noise voltage, A-weighted, inputs shorted

  • -103 dBV, -101 dBu, 7.1 uVrms, Stereo Mode
  • -100 dBV, -98 dBu, 9.8 uVrms, Mono Mode

Use dBV to calculate the SPL of the noise produced by your speaker/amplifier combination. Use the following formula: Amplifier output noise voltage in dBV + speaker sensitivity at 2.83V - 9 dB. Example: Mono mode driving very high efficiency speakers: (-100 dBV) + (104 dB SPL @ 2.83V 1m) - 9 dB = -5 dB SPL at 1 meter. This means that the system noise will be 5 dB below the threshold of hearing when driving speakers with a very high 104 dB efficiency.

    Noise Relative to 2.83 Vrms

    Output noise relative to 2.83 Vrms, A-weighted, inputs shorted

    • -112 dB, Stereo Mode
    • -109 dB, Mono Mode


    1 kHz, 80 kHz LPF, at full rated output into any rated load

    • < -118 dB (< 0.00013%), Stereo Mode
    • < -118 dB (< 0.00013%), Mono Mode


    1 kHz, 20 kHz LPF, at full rated output into any rated load

    • -119 dB (< 0.00011%), Stereo Mode
      • < -120 dB (< 0.00010%), Mono Mode


      • Better than -115 dB at 1 kHz
      • Better than -92 dB at 20 kHz

      Frequency Response

      • Better than 0.1 Hz to 200 kHz, +0/-3 dB
      • -0.01 dB at 20 Hz, -0.17 dB at 20 kHz, 8-Ohm Load
      • -0.23 dB at 20 Hz, -0.32 dB at 20 kHz, 4-Ohm Load

      Damping Factor

      • 350 at 20 Hz, 8-Ohms
      • 254 at 1 kHz, 8-Ohms
      • 34 at 20 kHz, 8-Ohms
      • 7 at 200 kHz, 8-Ohms 

      Maximum Audio Output Current

      • 29 A peak, per channel, both channels driven

      Input Sensitivity

      • Low-Gain = 22 dBu (9.8 Vrms), Gain = 9.2 dB
      • Mid-Gain = 14.2 dBu (4 Vrms), Gain = 17.0 dB
      • High-Gain = 8.2 dBu (2 Vrms), Gain = 23 dB
      • Use Mid-Gain or High-Gain settings for unbalanced inputs
      • Unbalanced inputs require RCA to XLRM adapter cables 

      Input Impedance

      • 50 k Ohms, normal mode
      • 1 M Ohm, common mode

      Input CMRR

      • 80 dB at 20 Hz, typical
      • 80 dB at 1 kHz, typical
      • 65 dB at 20 kHz, typical

      Trigger I/O

      • 12 VDC 200 mA current-limited output to trigger turn-on of remote devices
      • DC input for slaving to remote devices
      • Input responds to 3.3 V logic and higher, VIL = 1.26 V, VIH = 2.7 V
      • Absolute maximum input voltage = 30 VDC
      • Absolute minimum input voltage = -0.3 VDC
      • Input Impedance = 20 k Ohms

      Protection Circuits

      • Fully Electronic, No Relays
      • Mute Sequencing
      • Distortion Detection
      • Short Circuit Detection
      • Over Current Detection
      • Over Temperature Detection
      • SOA Detection (Output device safe operating area)


      Non-rack-mount version:

      • 11.04" W x 3.88" H x 9.34 " D - Including feet and binding posts
      • 11.04" W x 3.47" H x 8.33 " D - Excluding feet and connectors
      • Faceplate height is 2RU

      Rack-mount version:

      • 19.00" W x 3.88" H x 10.62 " D - Including binding posts, handles and removable feet
      • 19.00" W x 3.47" H x 8.33 " D - Excluding feet and connectors
      • 9.09" rack depth, including binding posts, excluding cables
      • 11" rack depth, including cables
      • Faceplate height is 2RU


      • 12.5 lbs., 16 lbs. shipping - Non-rack-mount version
      • 13.5 lbs., 17 lbs. shipping - Rack-mount version

      AC Input

      • Auto-ranging AC Input
      • 100 to 120 VAC +/- 10%, 8 Amps, 50 - 60 Hz
      • 220 to 240 VAC +/- 10%, 8 Amps, 50 - 60 Hz
      • Idle Power Consumption = 20 W
      • Standby Power Consumption < 0.5 W

      Read Sterephile's Review of the AHB2 here.

      This forum post discusses the use of AHB2 as a headphone amp.