Benchmark AHB2 Amplifier with THX AAA Technology Arrives for Review



Benchmark Media has long established itself as one of the premier global manufacturers of digital to analog converters, commonly known as DACs.  Benchmark’s DAC1 and DAC2 have won rave reviews and a loyal following for their exceptional performance and impeccable build quality.  While Benchmark’s DACs have always featured excellent headphone amplifiers, the company had never entered the amplifier market in any serious capacity.
That all changed thanks to THX.  THX’s revolutionary Achromatic Audio Amplifier (AAA) technology boasted vanishingly low distortion and an unbelievable signal-to-noise ratio (SNR), and feed forward design, among other features.


The AHB2 user manual provides extensive measurements of the unit including THD vs. Output power into 8 Ohm and 4 Ohm loads; THD vs. output power in bridged mono; damping factor; and FFT plot at 320W, 1 kHz, 8 Ohms bridged mono.
This new technology promised to be a perfect compliment to bring out the full performance of Benchmark’s DACs.  As you can read in my in-depth interview with THX’s Senior Vice President of Audio Research, Laurie Fincham, THX and Benchmark worked together to develop the first commercially available amplifier based on THX’s AAA technology, the Benchmark AHB2 power amplifier.  This was a technology and product that was over nine years in the making.
Following my interview with THX’s Laurie Fincham, I was certainly excited to get the Benchmark AHB2 (MSRP $2,995) in for review.  As you’ll quickly see, my initial impressions easily lived up to all my expectations.
I had the pleasure of coordinating my review with Benchmark’s Technical Chief, John Siau (I’ll have a more in-depth technical discussion with John in the forthcoming, full review of the AHB2). In order to appreciate the SNR of the AHB2 amplifier, John suggested that I pair the AHB2 with one of Benchmark’s own DAC2 HGC units. The DAC2HGC ($1,995 MSRP) has both analog and digital inputs so that I could use it with any source.  Benchmark also sent me a 15-foot pair of their NL2 to Banana 2 pole speaker cables (MSRP $95) so that I could connect to the AHB2 amplifier’s native SpeakON output connectors.

Packaging and Branding

Benchmark’s packaging and branding were impeccable.  The AHB2 was packaged with co-branded taping that featured both the THX and Benchmark logos.
The AHB2 Power Amplifier Comes in packaging that is co-branded with THX and Benchmark’s logos.
The same attention to detail and quality packaging was evident with the Benchmark DAC2 HGC.
The Benchmark DAC2

The packaging offered solid protection for the unit.

The included remote control for the DAC2 HGC is made of high quality aluminum.  There’s nothing at all cheap or flimsy about it.  The heavy duty Energizer industrial grade batteries and spare fuses were another nice touch—no shortcuts.
Included accessories with the Benchmark DAC2 HGC
As with the DAC2, opening the AHB2 box showed that the AHB2 was very well packaged and would easily survive significant mishandling.  The THX Logo once again greets you when you unpack the amplifier.

First Impressions on Build Quality and Connectivity Options

The AHB2 contains an extensive instruction manual as well as a nicely done marketing brochure to introduce the user to the AAA technology in the Benchmark AHB2.
Inspecting both units up close, I noticed some blemishes and an occasional light scratch here and there.  I also noticed that the bottom of the units were specially labeled as DEMO and PROMO.
The Benchmark AHB2 power amplifier listed its manufacturing date followed by a DEMO label.
I asked the folks at Benchmark about this.  I was told that the chassis of the units were B-stock but that the internal build parts were A-stock.  They were running low on stock and wanted to get review samples into my hands.  I appreciated this effort!   Having units with a B-stock chassis explained why the cosmetics weren’t 100% perfect.  If you happen see such imperfections in any of the following photos you’ll then know why.

AHB2 Amplifier

Looking at the AHB2 amplifier, you just can’t help but scratch your head as to how small this thing is.     It’s tiny.  Yes, I’ve seen and used  tiny Class D amplifiers.  This isn’t the same thing.  This is unlike any amplifier you’ve ever seen and you’re left asking yourself, “Will this thing really drive $500, $2,000, $10,000, or $20,000+ speakers?” It’s like someone took a huge Class A amplifier and shrunk it by 50%-70%.  That’s perhaps the only way I can describe it.  It only took up about 1/3 of my shelf!
Small as it is, it feels like a premium, audiophile amplifier.  Its all-metal construction gives it serious heft and weight.  There isn’t anything—anything at all—flimsy about it.
As you unpack the accessories and look at the amplifier in detail, you’ll immediately notice that this unit has been specifically designed to handle the rigors of professional use.  A telltale sign of pro gear is locking connectors.
In the pro world, when you plug something in you want it to stay connected. Accidental pulls are a no-no.  Therefore in pro-gear, your plugs lock.  It’s as simple as that.
The AHB2 shows this pedigree by including a locking power cord.  Insert the AHB2’s included power cord and it will lock in place.  To unplug it, simply depress the red button on either side of the cord to release it from the unit.  Of course, you can use a non-locking cord or any standard IEC power cord.
Except for the standard speaker binding posts, all inputs and outputs on the AHB2 are likewise all locking.  There are no unbalanced/RCA input options.  If you have a preamplifier with unbalanced connections and you want to use the AHB2, then Benchmark sells RCA to XLR adapter cables.
The rear of the AHB2 emphasizes locking connectors for input and output.  Benchmark sells RCA to XLR and SpeakON to banana cables so users who don’t have the appropriate connectors can use the AHB2 without issue.
As I mentioned, Benchmark sent me locking speaker cables to use with the AHB2 in addition to my standard speaker cables.  The Benchmark NL2 to banana cables are again high quality (have you noticed the theme here yet?).  The cables are 11 AWG and have a pair of 14 AWG conductors in a star-quad configuration.  I personally use a set of Audioquest speaker cables featuring two pairs of 14 AWG conductors in the same star- quad configuration for years.
The Benchmark Speaker Cable
A heavy-duty 40 Amp locking Neutrik NS2FX connector sits on one end and heavy duty locking banana connectors are on the other end.
The Benchmark cables are high quality Canare star-quad speaker cables terminated with Neutrik NS2FX connectors on one side and heavy duty locking banana connectors on the other end.
I wish more audiophile amplifiers featured the SpeakON connectors.  I love them.  Connections are simple and secure.  There’s no second guessing.  Trust me, once you use the SpeakON connections on the AHB2 you’ll rue the day you have to go back to standard banana cables, spades, or bare cable.
Let me say it perhaps more emphatically: The AHB2’s build quality represents the best that “Made in America” signifies.  The materials, craftsmanship, and design are all top-notch.  Everything with the unit is clearly and logically labeled.
The THX technology logo is discreetly yet prominently featured on the left rear of the unit near the five way binding posts.

The AHB2 will easily fit into any audiophile or professional setup.  There are dual 12v triggers that function as bi-drectional inputs and outputs.  One 12v trigger is located on the right and the other on the left.  You have infinite flexibility on how to run your cables and daisy chain multiple units in your setup.

The right rear of the unit features a 12V input/output trigger as well as a stereo or monoblock mode switch.
The left side of the AHB2 amplifier also provides you with a toggle switch to use the amplifier in its default stereo or in a bridged monoblock mode.  If you switch the unit into bridged monoblock mode, there’s a dedicated SpeakON connector in the middle of the unit dedicated just to this mode.

The left rear of the unit sports a sensitivity switch.  This switch sets the amplifier gain.  It will help match the amplifier to maximize the signal to nose ratio of your audio system. According to Benchmark, if you set the switch too low, you won’t be able to drive the amplifier to its rated output.  If you set the switch too high, then the noise produced by your preamp will be amplified more than necessary.  The included user manual gives you all the guidance you need to set the switch properly.  
If you are feeding from a Benchmark DAC1 or DAC2 converter, set the switch to minimum gain (bottom position). The Benchmark converters have studio-level balanced outputs that reach +24 dBu at full scale. High-level interconnects are standard in professional applications because they provide the best system SNR performance.  In case you are wondering, yes, you can also use professional balanced sources with the AHB2 by setting the gain switch to minimum.
The front of the unit contains more status lights than audiophiles are likely accustomed to—and this is a good thing.  Normally, audiophile power amps are minimalist.  They will have a power status LED and perhaps a channel light.  If there’s a fault, the channel at fault will normally blink.  I’ve always found this approach way too limited and I love what Benchmark did.  You have an LED for power, a separate pair of LEDs for mute, temperature fault, and clipping.  There is a set of LEDs dedicated to each channel.
The AHB2 user manual provides you with a comprehensive matrix of possible fault conditions and how the status lights show you specifically what the fault condition is.  The AHB2 can tell you if you have a problem with clipping, over current, temperature, a power supply fault, etc.
When you power up the AHB2, it goes through a power on sequence as you can see in the image above.  Before the amplifier goes into its operating mode, it will mute both amplifier channels so you don’t experience any pops or other surprises.  Only then will the amplifier go into full operating mode.
As you’ll see in the forthcoming full review, these status lights came in super handy in helping diagnose a problem that arose during the review period with the Revel Ultima2 Salons that I paired with the Benchmark AHB2.  That’s right, we’re going to pair this setup with some of the most critically acclaimed speakers on the market today.

The AHB2’s Auto Shutdown Feature

An item I wanted to note the AHB2’s auto-shutdown feature.   By default, the amplifier is set to go into power standby after 45 minutes of non-use.  In other words if there’s no audio signal to the amplifier it will automatically turn off.  This is a great feature to save power but may have some unintended consequences.  For example, when the AHB2 executes an automatic power down, it will also pull the 12V trigger to shut down any equipment chained to it.  You’ll therefore need to plan your audio architecture accordingly.
What’s a bit unusual about the AHB2 power down is that if you then send an audio signal after 45 minutes, the AHB2 won’t auto-power back on.  There’s no auto signal input sensing mode.  You’ll manually need to power the AHB2 back on.

Summary of Initial Impressions

To summarize, let me just say it again: The AHB2 and DAC2 HGC were an absolute joy to unpack and admire.  The units are just beautiful, wonderfully well thought out, and built like tanks.   Integrating these into my existing setup was a breeze and I had loads of flexibility.  I can’t imagine an environment where you’ll be stumped.
These are audio investments that scream quality and are made for years and years of reliable, high performance use.  You can tell that Benchmark has paid attention to detail throughout the industrial and technical design of these units.
Minus the B-stock condition of the chassis, I couldn’t find a single thing to fault or criticize with either unit.  I’m looking forward to taking the AHB2 THX-technology driven amplifier for a serious workout and experience what the Benchmark DAC2 will bring to the table.
Stay tuned for my full review.  If this preview is any indication, this should be one seriously fun ride.