Hardware Reviews

Benchmark DAC3 HGC & AHB2 no frills fun

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp review https://the-ear.net

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp

I suppose it’s having grown-up with it, as it were, in my early BBC days but I just love the look, feel and operation of professional audio equipment. When the chance presented itself to try some Benchmark electronics from the US, I just could not resist. Two boxes arrived: the DAC3 HGC preamp/DAC and the AHB2 100 Watt stereo power amp which can be bridged to create a 380W monoblock. I had a feeling this was going to be fun.

Benchmark

Dating back to 1985 and based in Syracuse in New York State, Benchmark is run by a mix of musicians, audiophiles and professional audio engineers. So, while sound quality is paramount so too is durability and build quality. Engineering director, and now part-owner, John Siau joined the company in 1995 with wide industry experience including spells at CBS and General Electric. His first design at Benchmark was a 20-bit A/D converter that set new standards for low-distortion. A musician at heart, he plays trumpet and tuba.

Acknowledging that the human ear/brain must be used alongside sophisticated measurement equipment, John says that listening is the final test before a design passes from R&D to production. But cautions not to simply listen-tweak-listen since that can merely mask an artifact with another less-objectionable one. However, eliminating every artifact measured is the route to sonic transparency.

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp review https://the-ear.net

DAC 3 HGC design

While it is a preamplifier with a DAC catering for discrete digital and analogue component to be connected, there is no streaming functionality as is the case with many hi-fi products of this ilk. Studios will be generating their own sources to create commercial recordings, rarely wanting to stream them.

The instruction manual supplied is one of the most comprehensive I have seen, all 72 pages of it, and takes me back to my studio days where equipment would have ring-binders full of data sheets, plots, circuit diagrams and more. With much hi-fi kit one is lucky to find a small card at the bottom of the packaging with a QR code linking to some meagre online booklet, usually scant. The Benchmark booklet outlines all the features and circuitry and details the set-up procedure very clearly, even mentioning what it can’t do. You don’t’ find those admissions with domestic gear!

This unit is similar to those supplied to the famous Abbey Road and other prestigious studios, so we are in good company. The DAC3 boasts lower distortion than the earlier model and its Quad 32-bit balanced DAC is based around Sabre’s tried and tested ES9028Pro circuit. This IC has two distortion compensation systems that independently remove most of the 2nd and 3rd harmonic distortion in the D/A converter.

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp review https://the-ear.net

A bonus here is the inclusion of a fine quality preamp stage which handles both the analogue and digital inputs although with separate volume circuits, both using the same control function. Selecting inputs sees the volume control return to the last position used for the device. There’s the ability to apply pass through to any input so that the volume can be controlled upstream as would be needed in many studio applications but also useful for multi-room hi-fi application.

The digital inputs support native 192 kHz PCM or DSD64 conversion. Benchmark is proud not to have DSD to PCM or PCM to DSD conversions to compromise the quality. Conversion switches, seamlessly, between native PCM and native DSD conversion. This is probably why the numbers are not particularly high, ultimately quality is far more important that specifications in this department.

Unusually, there is an inversion switch to cope with any recordings that have inverted polarity. Also of note is Home Theater Bypass mode which sets the pass-through gain to unity when a surround system is active; and Digital Pass Through whereby a coaxial input can be reconfigured as a digital output, including Dolby digital and DTS encoding to feed a surround processor. That so much technology is packed into such a compact enclosure is truly impressive but I have to make mention of the onboard headphone amplifier which I found to be of superb quality when assessing HEDD’s Heddphone 2 recently.

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp review https://the-ear.net

AHB2 design

Rather more conventional, externally at least, is the 100W/ch (8 Ohms) stereo power amplifier, bridgeable to create a 380W monoblock. Even then, under the lid it houses some interesting circuitry. For one thing, Benchmark has teamed up with THX and abandoned conventional amplifier topology. Key facets through the design process were frequency response, output noise, drive current, damping factor, and reliability.

Featuring the patented THX AAA technology to virtually eliminate all forms of distortion, Benchmark’s aim was to deliver the best performance characteristics of a Class A amplifier and yet remain crystal clear when delivering high power into ‘difficult’ speaker loads.

Certainly, the units runs a lot cooler than most hi-fi designs I’ve encountered and features passive cooling. In this regard, Benchmark say that it resembles many Class D switching amplifiers, even though it’s not one. Instead we have a linear Class H amplifier with bipolar output transistors and a unique THX feedforward error-correction system which corrects errors before they reach the output.

Being ostensibly a pro unit, input is via balanced XLR sockets and speaker outputs include Speakon connectors alongside binding posts to accepts banana plugs, spades or bare wires. The front panel bristles with LEDs alongside the power switch, we have clip and high-current indication per channel, and mute indicators. Of importance is the sensitivity selector to maximise the signal-to-noise ratio and drive the amp to its rated output. Again, the comprehensive instruction manual (just 40 pages this time) details everything very clearly.

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp review https://the-ear.net

Set-up

The first thing I noticed, unboxing and connecting the equipment was how well made the units were. No flimsy casework which yields to the fingers here, as in so much hi-fi. And I felt confident in leaving the amplifiers powered, something I am reluctant to do with many domestic products.

I began with the DAC3 HGC and AHB2 powering the glorious Morel Avyra 633

three-way floorstanders. Sources included an internet tuner (digital coax), an Escape M1 Air streamer (via optical) to access Apple Music, and my satellite receiver via another optical input. The pre and power amps were connected together by balanced XLR cables.

To begin with I have to confess that I found the units rather awkward to use, they lack some of the frills that we get used to on hi-fi equipment, not least app control. However, after just a couple of days I found that I was operating them like a pro and could settle down to enjoy the sound quality. I left them in my system for a couple of weeks and then got down to auditioning.

Sound quality

Selecting one of the very few decent recordings featuring Gerry Rafferty, I began with The Right Moment from his Sleepwalking album which begins rather slowly and relies on a lot of 80s synths. There are some fine moments in the music that allow the performer’s depth and artistry to come through given the right equipment, and the Benchmark/Morel combination certainly showed that they were up for the task. This track can sound really dirge-like, morose even, but this pairing created such a full-bodied sound which brought the recording to life that I not only survived it, I enjoyed it.

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp review https://the-ear.net

Notable from the off was the bass from the DAC3 HGC and AHB2. Yes, I was also aware of how quiet they were, an eerie quietness in the silent parts, but the strength of the bassline was palpable and made me think I had connected amplification valued at several times the price. Wow! It was deep, tight and conveyed a real feeling that the electronics were in charge of the transducers.

Keeping to the same era, Simon and Garfunkel’s Baby Driver (Bridge Over Troubled Waters) might be an old analogue recording but one that really came to life with this set-up. Involuntary foot-tapping confirmed the timing ability and the overall presentation was spot-on, the Benchmark electronics created a fluent sound across a vivid soundstage; performers evident both tonally and spatially in an easy-to-believe presentation that brought the performance close. Not an unnatural, unpleasant ‘in your lap’ close, just vividly so; an at arms’ length presentation that appears natural, even down to the vocal twang. The final engine sound effect had such an amazing stereo image that it made the hairs on the back of my neck tingle. Increasing the volume merely increased the enjoyment, and that can’t be said of all amplifiers. But because the Benchmark has a very carefully controlled power supply, to prevent clipping or distortion appearing on the output, it’s a safe move with the AHB2 and I didn’t manage to make the clipping indicator even flicker.

Switching to my Revival’s Atalante 3s and a change of genre to Shostakovich’s 24 Preludes & Fugues(Ashkenazy on Decca from 1999) and I was presented with an extremely realistic sound across an open and wide soundstage. In fact, the more classical material I listened to, the more I realised that the Benchmark’s ability to retrieve deep-down detail and display it so well across the soundstage, with accurate positioning and convincing layering, made for a glorious re-creation of the recordings. So it was with Hayden’s London Symphony 104 (BPO/Karajan) from 1975. As the work erupted with that blaze of light I nearly jumped out of my seat, the sound of the majestic fanfare so forceful, so realistic before it morphs into the subdued and atmospheric adagio introduction. The piece’s grand gestures and rustic charm came across so well as to have me captured. This is a performance both muscular yet delicate, combining power and gracefulness but all handled without hesitation by the AHB2, while others I can recall have faltered.

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp review https://the-ear.net

Switching to speech-based material and some BBC Radio recordings of Rumpole with the voices of Benedict Cumberbatch, Timothy West and Prunella Scales, it’s clear that Benchmark have created a very neutral and honest-sounding amplifier. The output is audibly linear with no apparent anomalies to jar the brain when listening to the drama production. This might not be to everyone’s taste and it will depend on how much character the connected loudspeakers have. But, for my ears, this was just the perfect partner for Revival’s little monitor speaker.

Staying with the Revival speakers and before packing the Benchmark units, I connected the variable output of the new Hegel H190v streaming amplifier to the AHB2, using its streamer/DAC and preamp stages. The result was simply stunning and I can easily see this power amplifier finding favour with audiophiles; better still, a pair in bridged mode since they will create a glorious sound.

To my mind the AHB2 is an amplifier with no obvious characteristics of its own: the level of transparency is sublime. With a range of tunes I have been playing a lot lately (by George Ezra, Sheppard and Semisonics) the result was entirely pleasing. The immense level of detail coming forward was just extraordinary, I had no idea my favourite integrated streamer could be so transformed, and all for a power amp costing about the same again. Incredible. Above all, the improved transient response performance stood out in a presentation that was not only lively but incredibly fast and revealing. The attack and decay displayed was awesome and not something I expect at this price point.

Benchmark DAC3 HGC DAC/pre and AHB2 stereo power amp review https://the-ear.net

Conclusion

The Benchmark DAC3 HGC and AHB2 are cracking products, sonically superior to a lot that’s available and well priced. I’ve heard the word utilitarian used to describe Benchmark designsbut that does them rather a disservice. They are superbly designed and built to an extremely high standard. Because they are intended, first and foremost, for use in studios they lack some of the frilly bits that we are used to on pure hi-fi products. This therefore makes them rather ‘clunky’ to use in a domestic setting where we are used to ease of control.

The fact that both these units are so compact, diminutive even, will mean they find favour with those who simply do not have space for full-width hi-fi boxes, many of which are half-empty anyway. That said, I do feel that if the high-quality circuits were placed into larger cases (the DAC3 HGC especially), with some flashy interface, they’d gain popularity in audiophile circles. I can hear calls for a phono stage to be included but, from my point of view, a streamer would be the ideal candidate to include in the DAC3 HGC, and one controllable using a UPnP app if possible.

As it stands, they offer value-for-money and produce stunning sound quality, surely key prerequisites when selecting equipment. The AHB2 stereo power amplifier, in particular, is something I could happily live with.

Specifications:

DAC3 HGC
Type: preamplifier and digital to analogue converter
Distortion THD+N: -119 dBFS, -116 dB, 0.00016% @ 1 kHz at –3 dBFS
Signal to noise: 128 dB A-weighted, 0 dBFS = +27 dBu
Digital Inputs: USB 2.0, 2x coax on RCA, 2x optical on Toslink
Analogue inputs: 2x RCA
Wireless inputs: none
Headphone output: 6.3mm jack
Analogue outputs: 2x single ended RCA, balanced XLR
Supported sample rates: PCM up to 24-bit/192kHz, DSD64
Output Voltage: not specified
DAC chip: ES9028Pro
Accessories: remote handset
Dimensions HxWxD: 44.5 x 249 x 216mm
Weight: 1.3kg
Warranty: 1 year (2 years with registration)

AHB2
Type: stereo power amplifier.
Analogue inputs: XLR
Analogue outputs: binding posts, Speakon
Power output: 100W/8 Ohms, 190W/4 Ohms
Frequency response: Better than 0.1 Hz to 200 kHz, +0/-3 dB
Sensitivity: 14.2 dBu (4 Vrms)
Gain: 17.0 dB (mid gain)
Distortion THD+N: < -118 dB (< 0.00013%) stereo
Signal to noise ratio: 132 dB A-weighted stereo
Dimensions (HxWxD): 98.5 x 280 x 211.5mm
Shipping weight: 41kg
Warranty: 1 year (2 years with registration)

Price when tested:
DAC3 HGC £2,449
AHB2 £3,749
Manufacturer Details:

Benchmark Media Systems
http://www.benchmarkmedia.com

Type:

DAC/preamplifier & power amplifier

Author:

Trevor Butler

Distributor Details:

SCV Distribution
T 03301 22250
http://www.scvdistribution.co.uk

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