Benchmark’s AHB2 Stereo Amplifier

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Achieving the full performance/responsiveness out of my speakers has motivated me to examine various amplifiers designs lately. In this quest to squeeze the last sound molecules from my speaker drivers, I have been comparing class A, Class A/B, Class D, and now this hybrid Class H and AB design from Benchmark and THX.

Delivering clean power with an exceptionally low noise floor are the key ingredients to Benchmark’s new Amplifier. The AHB2 is a 2 channel audio amplifier with 100 watts of power into 8 ohms, and 190 into 4 ohms(bridged mono mode 380 watts/8ohms). This super quiet amplifier topology allows for a signal-to-noise ration of 130dB unweighted. The distortion is also quite low, at 0.00011% THD in stereo mode.

With a clean and tidy footprint, The front panel allows access to 1 power button, and several LEDs that indicate proper operation. Benchmark built into the AHB2- a power supply fault protection to monitor voltage, current, and temperature. If issues arise, the fault circuit mutes both channels to protect the amplifier and speakers. The clip lights will illuminate when occasional clipping is present (something that never happened for me), and the fault protection kicks in when severe overdrive occurs- to protect speakers.

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On the business end of things, connectivity is straight forward. Other than the addition of Speakon connectors, the Balanced XLR inputs and speaker terminals are standard. One dip switch on the right controls mono or stereo operation, while the 3 position switch on the left controls input sensitivity – a welcome feature. Matching the input sensitivity allowed me to optimize the Gain control between the Crane Song Avocet and the AHB2.

Technically speaking, the AHB2’s Vanishingly low noise floor can be compared to the dynamic capabilities of a 22-bit digital system. Most current professional and audiophile DACS can also achieve very low noise floors – a match made in audiophile heaven.

I used the Crane song Avocet and several other DACs to feed Balanced stereo program material to the AHB2. For speakers I used my Green Mountain Eos HX 2-way speakers. All cabling was balanced solid core copper.

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The tidy AHB2 Amp runs cool

I gave the Benchmark amplifier some time to warm-up and have had it in my system for several weeks. My initial reaction was in the form of a grin, as I heard my music amplified in a clear and coherent manner. The extremely low noise floor became revealed as orchestras truly faded to the acoustic space and black was truly black – no residual noise whatsoever from speaker drivers. Even more obvious was a clarity to the amplification. This amplifier runs like a high-performance sports car. I was amazed at the AHB2’s ability to keep up with dense music mixes and never sound congested or lacking. In fact, this tidy beast produced some of the tightest low end I’ve ever heard in my 2 way speakers. The midrange was articulate and clear with an obvious clarity that bested my current class A/B amplifier. Extending to the high frequencies were equally clear and distortion free, no hype here- just honest clean reproduction.

Listening to Beck’s “Morning Phase” (24/96) was ear opening and lovely on the AHB2. The track “Morning” enters with  acoustic guitar strumming and stereo vocals, and leads into lovely strings with reverberant stereo space all around. Even with this wash of sounds, the hit of the Floor tom, or the crisp full fleshed out sound of the snare was colorless and clearly projected.

The Royal Liverpool Philharmonic’s performing Hovhaness’ Mysterious Mountains (Telarc 16/44.1) was sublime. Mount St. Helens Andante, Grazioso unfolds gracefully and with tip top double bass walking the piece along. The bass holds true and rings out even as the full strings come into glide the momentum along. The expansiveness of this orchestral recording is deep and wide with excellent localization. Acoustically, the AHB2 performs so cleanly and quietly that it resolves the hall and space between musicians distinctly- something professional engineers and audiophiles can equally appreciate.

The Benchmark amplifier allowed for dense music mixes to be fully appreciated. Micro-dynamic detail was never lost or distorted, even as complex passages competed. Orchestral and Popular music mixes equally excelled on the AHB2 with authority, control, and balanced sonic presentation. If you are looking for an amplifier that can reveal your source material and DAC without flinching, then the AHB2 is a top choice.

Happy Listening,

HiFiQC

Photography: Vahan Baladouni

 

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