AHB2 Review - Sandu Vitalie, Sound News

Video Review

Excerpts from Printed Review

"Benchmark Media doesn’t need an introduction whatsoever, as their name implies - they’re committed to excellence. Besides bestowing world-class specifications, everything they make is backed-up by measurements produced by the world’s best audio analyzers."

"Luckily, Benchmark’s crew isn’t formed only by nerdy engineers, as you’ll find musicians, audiophiles and audio professionals throughout their ranks that don’t care only for the numbers (measurements), but for the end result as well."

The HPA4 Headphone/Line Amplifier

"I was given the privilege of reviewing the world-class Benchmark HPA4 preamp and headphone amp some time ago, that in time became my daily driver work horse. You can see it everywhere around here, it was put in at least ~40 reviews as all my headphones, DACs and power amp reviews were made with its help."

"It was both technical & linear sounding…and between you and me, this is exactly what I’m searching with all amplifiers that are passing though my hands: a metal box that will preserve the soul of the music, without adding or subtracting anything from there."

The AHB2 Power Amplifier

"AHB2 might look small and lightweight, but thanks to its clever engineering and power supply implementation, this little fellow could still deliver 190 Watts in 4 Ohms and 100 Watts in 8 Ohms, while maintaining an undetectable noise floor and distortion."

"For the craziest folks out there, you can even bridge two pieces together for ~580 Watts in 4 Ohms and 380W in 8 ohms."

Build Quality

"Thor almighty! This thing has some amazingly thick panels all around it, adding a level of confidence and refinement. It looks plain and industrial, but I really dig its minimalist body."

"Thanks to its massive heat-dissipation fins, AHB2 runs very cool when idle and it remains as cool under most load conditions. It can get a little warmer under harder loads, but it was never hot under any circumstances."

Controls & Connectivity

"Being a power amplifier only, you won’t find remotes and volume controls with this one, there’s only a single On/Off button and several LEDs will be showing if it reached an over temperature, over-current, or clipping status and everything else is located on its back. There you’ll find your left and right speaker terminals, an AC socket in the middle, a pair of balanced XLR inputs and three NL4 speaker outputs (also called as SpeakON terminals) - that are mostly used in the Pro Audio world."

"This is a balanced only amplifier, so you won’t find single ended RCA inputs. A switch lets you choose its sensitivity depending on how powerful is your source. You can select between 2, 4 or 9.8 V inputs and another switch lets you choose its stereo or mono (bridged) operation. For mono mode, you will need two AHB2 power amplifiers."

Protection Systems

"You know what I like the most about it? Its bullet-proof protection systems!"

"Its protection systems will monitor its output voltage, output current, output distortion, output device SOA (safe operating area), power supply current, power supply voltage, AC line voltage, case temperatures and power device temperatures. Fault conditions silently mute both output channels in order to protect the speakers and amplifier from any damage. A status display shows the exact cause of the fault and the issues can be remedied in no time."

"As you well know, I’m switching digital sources on a weekly basis ... some of them offer preamp functionalities, while others don’t. I’ve replaced the excellent Gold Note DS-10 Plus & PSU-10 Evo stack with the SDA-6 PRO and I somehow forgot that the later doesn’t have a volume control, blasting 380Watts of power into my KEF Reference 3 after pressing the play button."

"A microsecond didn’t pass and both AHB2 engaged their protection circuits and muted themselves without causing any harm to my loudspeakers. For almost a year now, AHB2 saved my speakers twice."

Performance

"Benchmark is describing it as the quietest and cleanest audio amplifier on the planet. Some very powerful words right there, but considering its measured performance, AHB2 is still unrivaled by any other power amp when it comes to THD, Noise and dynamic range. I mean just look at those numbers. Show me another power amplifier than can deliver a measured dynamic range of 132 dB in stereo mode and 135 dB in mono mode and a total harmonic distortion of 0.00013% at Full Power."

Replacing Energy Storage Capacitors with Active Regulation

"Most high-quality power amplifiers have linear power supplies, large toroidal transformers and large banks of energy-storage capacitors. These linear supplies are sometimes unregulated and the capacitors help to remove ripple produced by the AC line. In contrast, AHB2 uses a tightly regulated resonant switching mode power supply that includes a very fast control loop. This control loop responds to audio-frequency load changes and keeps the supply voltage constant without the use of a large bank of capacitors. This active regulation is considerably more effective than capacitive energy-storage."

Test System Configuration

"AHB2 was used in a stereo setup and also in a headphone-based setup and yes, you’ve read that right!"

"I wanted to squeeze the last drop of performance out of it and that’s why I’ve used three different loudspeakers ..."

"AHB2 were also used in a headphone setup, directly driving a pair of Hifiman Susvara, which I already discussed in detail in my Hifiman Susvara review."

Driving KEF Reference 3 Loudspeakers

"Reference 3 are by far, the pickiest loudspeakers I’ve had in a very long time."

"When AHB2 replaced the S300, there were several immediate changes that jumped at me and those were absurd amounts of details coming forward that I didn’t encounter before, the speed and subsequently the impact of the sound drastically improved as well. The whole transient response jumped to a higher level altogether. Reference 3’s piston firing aluminum drivers are already known to be extremely fast and revealing sounding, but AHB2 added an iron grip, better controlling their attack and decay."

"The key words with AHB2 are: world-class detail retrieval, absolute transparency, lightning-fast transient response, an open wide soundstage with a very precise layering and positioning of the notes around the listener, all tightly controlled with an iron grip, never sounding too mellow, sluggish or all over the place."

My Conclusion

"The highest compliment I can give to AHB2 is that I purchased not one, but two units with my hard-earned money. These weren’t loaner units and this wasn’t a sponsored review and you can draw your own conclusions."

"If you’re searching for an honest, ultra-revealing, noiseless, transparent, lightning-fast and hard punching amplifier that wouldn’t limit the air travel, while providing an excellent imaging and depth, then AHB2 is one of the most impressive amps that passed through our HQ."

- Sandu Vitalie, SoundNews.net

Read the full review here →