March 2009

Benchmark DAC1 USB As A Headphone Amplifier
Impressively engineered, easy to set-up and operate... and dead quiet.
Review by A. Colin Flood
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  The Headroom Micro DAC and amplifiers reviewed in February 2009 are small, black, rounded and as adorable as a Mustang GT. The DAC1 USB however is a flat square. It is as wide as a hand, the size of a hard drive. The DAC1 USB face is a milled silver block of solid aluminum or black anodized, studded with black Torx screws and elegantly etched with the company name in cursive scroll. It is a book size miniature of the highest quality audio components. It is a stereo 24-bit/192-kHz Digital-to-Analog Converter with USB input, plus pre and headphone amplifiers. Think 500 horsepower crammed into sleek silver Vette.

Benchmark began in 1983. They manufacture equipment near Syracuse , NY , but do not have a showroom. Dick Oshler gushed over their similar DAC1 in April 2005. "The DAC1 defines digital playback that is exceedingly listenable with pop, jazz or classical music. Free from tonal balance distortions, it offers welcome relief from digital "heart burn" and eliminates the need for an exotic or expensive transport. Its well-defined bass range is another strong plus." Part of Osler's enthusiasm back then was the DAC1's price point below one thousand dollars.

Two years later, the DAC1 USB is $1,295 and yet Steve Stone still picked it over the Bel Canto's e.One Dac3 "since it nearly equals" the Bel Canto sonics, but at half the price. Stone warned that the "the flip side of integrating a smooth, neutrally balanced, component such as the DAC1 into an existing system, is that its naturalness may be initially mistaken for lack of drive or emotional involvement." Therefore, what Benchmark does not need is another rare review for one of their digital-to-analog converters (DACs). Thus, I reviewed it as a DAC/amplifier on my Audio-Technica ATH-A700 headphones.

DAChotomy
In electronics, a digital-to-analog converter (DAC) takes the music uploaded to a computer and massages it into a signal for the headphone amplifier. How well it does this determines how good it sounds. How well it does this determines if a $1,295 DAC is a great headphone amplifier. The DAC1 USB input is compatible with Windows Vista/XP/2000 and Mac OS X It does not require driver installation or system configuration. Benchmark does not recommend driving headphones from the rear outputs.

Compared to the DAC1Pre, the USB version uses National LM4562 op (chip) amplifiers in the output stage, whereas the DAC1Pre uses them throughout the analog stage, excluding the headphone stage. The DAC1Pre has different inputs and a mute function activated by the input selector. The DAC1 USB however, does not have any standard analog (RCA) inputs. Although I heard solid-state equipment warm up after a couple hours, Benchmark does not officially recommend a break-in period. Yet, with any electronic device, I like surge protectors of 1,000 joules with RFI and EMI protection or something like Quantum's Black Box Magic. With such protection, the DAC1 USB should last indefinitely. (Benchmark converters from 1996 are still in service.)

I asked how tweaking audiophiles could tell the difference between the specs of one DAC versus another. "Unfortunately," Rory Rall, Sales Manager said, "most DAC manufacturers won't publish the most important spec's... especially jitter attenuation, amplitude of jitter-induced sideband, and inter-channel differential phase. However, most manufactures will publish distortion spec's, and that can be a good indicator of overall performance. Unless there are significant differences in signal to noise ratio, that spec won't normally affect overall performance." The DAC1 USB puts out an inaudible 0.0003% Total Harmonic Distortion (with Noise) under full load.

Set-up Is Easy
Oshler and Stone covered the many possible connections that Benchmark crams onto the back of the DAC1 USB (everything), so I won't cover them here. Benchmark includes an A to B type cable that connects to a standard USB computer port. The manual is quite thorough. It is full size, 50-pages, with a set of charts and specs. I had to actually read it (who does that?) during set-up to discover five things:

In stark contrast to the smooth indentations of the block face, the sides of the thumb-size black volume knob are as rough as a cheese grater. The knob has a useful red dot to show its position. After set-up however, the only thing you have to touch is the knob. At first, I wished there were as many possible settings as my Behringer Ultracurve Equalizer, so I could make like a pilot and flip all sorts of switches before take-off. Not that you want a $1295 component to disappear into your PC system, but after awhile, I came to appreciate the knob's 41 possible settings, its tactile edges and the DAC's sonic invisibility. After a day of use, the unit is tepid to the touch, but never gets hot.

I now have four headphone amplifiers jumbled on the PC under my desk. The DAC1 USB came first, but because of its price and quality, I wish I could leave this review for last. I want to have the unit around to compare it to the $800 HeadRoom Micro combo, the $300 ASL tube HB1 and the new $200 Trend chip PA10 amplifiers. But that is not fair. I have always been a "first come, first served" reviewer. Yet my first impression of the DAC1 USB was not as good as the Headroom Micro combo at 2/3 the price....

Jimmie One
On the Led Zeppelin II, the opening riffs didn't grab me with their rasp and the piece didn't come alive. On "Whole Lotta Love," Robert Plant rips the album open with "You need coolin, baby!" But the DAC1 USB's version is cool, dry, faithful, and doesn't need "coolin." The bass is leaner and though possibly deeper, does not feel as if there was a subwoofer thrumming under my desk. Overall impression though was a very balanced, uncolored reproduction. The only nit I picked with my ATH-700 headphones was they didn't "feel as live as a full-size speaker does." The DAC1 USB does make music come alive with its energy.

Jimmie Two
On Diana Krall's "Jimmie" (Stepping Out, 1.4 Mbps wav file), the sensuous draw of the bow is rendered clean and tight, making the other amplifiers seem bloated. While the DAC1 USB doesn't grab with a wild interpretation, it feels smoothly accurate. Midrange is not over emphasized. There is no feeling of bloat or excess. Treble is straightforward and clean, without a lot of sparkle. The DAC1 USB sound is smoothly elegant, if not richly textured. Operation is virtually silent.

On a cheap pair of Sony ear buds, the Benchmark difference was obvious, but no big deal. The DAC1 USB certainly improved the bass and clarity. Yet the smooth capabilities of the silver server could not lift the tawdry buds to a new sonic level. I simply did not want to listen to the buds. Good quality headphones plugged directly into the PC provide better sound for the money.

In politics and audio reviews, "neutrality" is one of the most oft abused words. While being neutral can mean a piece of equipment is free from tonal balance distortions, it can also be mistaken for lack of drive or emotional involvement. Both descriptions are true of the DAC1 USB as a headphone amplifier. It is certainly trustworthy in its accuracy. While the Headroom Micro combo had more punch, forward presence and (with the Crossfeed circuit) more concert hall background air, the ASL and Trend tube amplifiers so far seem not only to have more color, more inaccuracies and (not surprising to tube lovers) more warmth.

Oh, drat! So what does this mean? Is this another solid-state versus tubes debate?

I am afraid so. On the solid-state side of the ring, I can't think of a better example of just how good a solid-state DAC and amplifier can be that the sleek silver DAC1 USB. It made the ASL tube and Trend hybrid headphone amplifiers seem overbearing and inaccurate. On the other hand, there is much to smile - and frown - about with the two tube amplifiers.

At home, on my big ole horns, I reached an excellent compromise: driving the ultra-efficient bass bins with a low-cost, but powerful, solid-state amplifier and the mid and upper range horns with delectable, but low-powered, tube amplifiers. Alas, I know of no such cost-effective solution for ear speakers (unless it is the new... review coming soon).

Solid-State Supercar
With Audio-Technica ATH-A700 and Headroom Micro combo, this is my third headphone component review. On the table below, three Blue Note means the performance in this category is average, with no obvious charms or serious weaknesses, compared to other units personally auditioned for Enjoy the Music.com. Rather than awarding four Blue Notes for lushness or warmth, I thought the DAC1 USB tonality was above average in its "neutrality." Compared to the other three amplifiers, I too thought it had a "well-defined bass range." The DAC1 USB dug deep in the bass, without noticeable boom. It is impressively engineered, easy to set-up and operate, and dead quiet. I did not suffer from "digital heart burn." All day use of the DAC1 USB did not wear out my ears, as so many solid-state components seem able to do. In my own personal category, Enjoyment, the DAC1 USB easily scores three Blue Notes.

Loudspeakers are the only bargain in audio: you get a lot of bang for the buck. Headphones are no exception. My own ATH-A700 headphones are a case in point. Therefore, it is not unusual to invest five to even ten times more than the cost of the speakers on quality front-end (and other) components. The DAC1 USB cost is not too far out of line for a superb quality audio system. If you want the sleek Vette, with 500 solid-state horses crammed under a silver hood at your desk, this is the ultimate DAC/headphone amplifier.

Specifications
Type: D/A Converter with USB Input
Digital Inputs: Three Coaxial, one Toslink, and one USB
Input Sample Frequency Range: 28kHz to 195kHz (Coaxial & Toslink); 44.1, 48, 88.2, 96 kHz (USB)
Maximum Input Word Length: 24 bits
THD+N: -107 dB, 0.00045% @ -3 dBFS input, -105 dB, 0.00056% @ 0 dBFS input
Crosstalk: -125 dB at 1 kHz

HPA2 Headphone Outputs
Output Impedance: < 0.11 Ohms
Maximum Output Current: 250 mA
Bandwidth: > 500 kHz
THD+N: -106 dB, 0.0005% into 30 Ohms at +18 dBu (1.26W)
Dimensions: 9.5 x 1.725 x 9.33 (WxHxD in inches)
Shipping weight: 7 lbs.
Price: $1295

Company Information
Benchmark Media Systems, Inc. 
203 East Hampton Place 
Suite 2 
Syracuse, NY 13206

Voice: (800) 262-4675
Website: www.benchmarkmedia.com