October 2007

The Nearfield
Two Digital Preamps...
Benchmark's DAC1 USB and Bel Canto's e.One Dac3
Article By Steven Stone

  You may well ask, "What defines a digital preamp?" Simply stated, a digital preamp is a two-channel preamp that accepts digital input sources and outputs variable level analog signals. It incorporates a fully featured DAC (digital analog converter) so in most cases it can handle not only 44.1kHz red-book CDs but also MP3s and 48kHz on up DVD soundtracks. Such a device can reduce the number of components in a system by at least one (an outboard DAC is no longer needed) and in the case of both the Benchmark DAC1 USB and Bel Canto e.One Dac3, since they both have USB input capabilities, a USB to SPIF converter box also becomes redundant. Both the Benchmark DAC1 and Bel Canto e.One Dac3 are diminutive enough to fit into a space smaller than shoebox. Small can be beautiful.

The Benchmark DAC1 USB
Everyone, including perhaps even Granny Smith in her Apple-Of-My-Eye My Space Blog, has reviewed the Benchmark DAC1 (including Enjoy the Music.com's senior editor Dick Olsher who review it at this link). Given its decidedly deep market penetration in reviewers' circles what more can I add to the copious utterances of shock and awe? Plenty. Most reviews have used the DAC1 in a room-based system, but its primary intended use is in a DAW (Digital Audio Workstation) environment. The Nearfield is where a DAC1 belongs. In such a desktop environment the DAC1 doesn't have to drive room-sized lengths of output cables. That's a good thing. Although it has both balanced and single ended outputs, many audiophiles (and reviewers) use single-ended RCA cables to drive long lines in a room-based system. Bad idea. In theory and practice single-ended outputs are not as sonically robust as balanced outputs and are far more susceptible to signal loss and EMF and RFI noise. Using the Benchmark DAC1's balanced outputs for long runs is fine since the DAC1's output circuits can drive 300-Ohm loads without a rise in distortion.

John Siau, the Director of Engineering at benchmark, says, "The DAC1 USB is equipped with low-impedance passive output attenuators that can be used to optimize the gain staging between the DAC1 and the power amp. This feature preserves the full dynamic range of the DAC1 over a 50 dB range of output levels. This is very important when interfacing directly with most power amps and powered monitors. Most amplifiers clip at about +4 dBu instead of at typical studio peak levels of +24 to +28 dBu. For this reason, the DAC1 ships with the 20 dB pads enabled. Also, please note that the output impedance of the passive pads is substantially lower on the DAC1 USB than it is on the classic DAC1. The DAC1 USB maintains its ability to drive long cables even when the pads are enabled"

Since it has both XLR balanced and RCA single-ended outputs, the DAC1 can be hooked up to a stereo amp through the XLR connections and to a subwoofer through the unbalanced RCA connections. That's just how I used it in my desktop system. For most of the review I used the Bel Canto S-300 power amplifier (reviewed here), Earthquake Supernova MK IV 10" subwoofer (reviewed here), and ATC 7 or Harbeth P-3 speakers. Sources included an EAD 8000Pro DVD/CD player, i-tunes from an Apple Mac Pro, and high-def audio from a Marantz PMC-671 96/24 recorder.

The Benchmark DAC1 USB has SPIF, Toslink, AES/EBU, and USB digital inputs. If you need to use an analog source you're out of luck, since the DAC1 is digital only. But for all you digital lads and lassies, this isn't a problem. The only controls on the front panel are the volume knob and a three-way input toggle switch. The backside has another toggle to go from fixed to variable output levels and a pair of small potentiometers for calibrating the fixed level outputs. The only signs of wretched excess on the DAC1 are the pair of headphone jacks on the front panel. Most headphone amp/preamps only give you one.

While I have no complaints with the DAC1's ergonomics or controls, I do wish the volume knob was a bit finer milled. It's so sharply machined that touching it is not dissimilar to fondling a rasp. I also wish the input switching was a bit more sprightly. You must wait several seconds after switching sources to let the DAC lock on the new signal. If you don't give it a count of one-one-thousand, two-one-thousand after switching inputs you may cruise right by the active input.

Sonically the Benchmark falls into the neat, clean, just-the-facts school of sound. It eschews any trace of euphony in favor of harmonic neutrality and straight-no-chaser low-level detail. The DAC1 is first and foremost a monitoring device. All the user can alter is the volume of playback. Given that its initial market was for professional recording engineers working in a DAW environment, its lack of controls or harmonic coloration makes perfect sense. If you like your music slightly warmed and a bit sweeter, the DAC1 isn't going to help you any. That's not its job.

With the right headphones the DAC1 makes a superb headphone amplifier. Coupled with my Grado RS-1 or Sennheiser HD580 headphones the DAC1 delivers enough clean gain to give your cilia a serious workout. Both of these phones also supply just a smidgen of euphonic warmth so the combination delivers very musical results. While I still prefer my Stax Lambda Novas driven by the Stax SRM-1/Ml-2 driver units for monitoring on-location recordings, at home in my desktop system the DAC1/ Grado combo provides more pleasing sonics with only the tiniest bit less upper frequency air.

Coupled to the Bel Canto S-300 power amp the Benchmark DAC1 nearly equals the recently reviewed Lyngdorf TDAI 2200. I still prefer the Lyngdorf because its room correction software produces a more tightly focused image and larger listening sweet spot. But compared with other non-DSP-enhanced systems, such as my Meridian 518/561 combo the Benchmark/Bel Canto rig displays an equal level of spatial finesse and slightly superior dynamic acuity. Again if you like a bit of additional warmth to the overall sound its gonna have to come from your transducers. The Harbeth P-3 speakers proved to be a better choice with the Benchmark/Bel Canto combo than the ATC 7's because the Harbeths have an inherently sunnier harmonic balance. On harsh pop recordings this combo proved to be non-fatiguing even after multiple hours of high volume level listening.

If you use your desktop system for DAW applications or if you demand an extremely neutral DAC/preamp the Benchmark DAC1 USB will do the job better than John Henry wielding a steam hammer. Given its very reasonable price and limited yet extremely useful set of features it's no wonder that the Benchmark has come to be the de-facto standard against which all other digital preamps are measured. Personally, I could happily live with a DAC1 for a long time. I suspect most audiophiles will come to a similar conclusion.

The Bel Canto e.One Dac3
The Bel Canto e.One Dac3 presents a different take on the digital preamp model. Instead of offering headphone amplifier functions, the Bel Canto delivers a few more inputs along with remote-control capabilities. Sonically the e.One Dac3 performs on a level equal to the Benchmark DAC1, but with some subtle sonic differences.

Physically the Bel Canto e.One Dac3 is slightly wider, taller, and deeper than the Benchmark DAC1, but will still fit comfortably into a half-rack space. With similar cosmetics to the other members of Bel Canto's eOne series of components, it features a 0.5-inch thick milled faceplate with a recessed oval insert that has a LED display and a large knob. The knob controls volume as well as the input source. To change functions you merely push the knob in and it clicks into its alternative signal selection mode. The LED readout supplies either output level or the input depending on your needs. While the

The rear panel has all the input and output connections, which include USB, optical, AES/EBU, and two coaxial SPIF inputs as well as both balanced XLR and single ended RCA outputs. The e.One Dac3 also has a small push button switch next to each XLR output that transforms its outputs from variable to fixed levels.

The Bel Canto e.One Dac3's remote control is a small oval shaped affair with only six buttons – volume up, volume down, Pre in, DAC in, and power on/off. It fits in your hand nicely. Although it doesn't light up the button arrangement makes it possible to tell the top from the bottom even in the dark.

So how does the Bel Canto e.One Dac3 differ sonically from the Benchmark DAC1? Frankly they are pretty darn close. The most noticeable difference is that the Bel Canto has a smidgen more dynamic authority in the lower midrange and upper bass. Both units project similar soundstage dimensions and harmonic balance and have the same amount of upper frequency air and delicacy. Both units also offer similar amounts of inner detail and resolution. Although I didn't attempt to perform any real-time matched level A/B comparisons, I'll go out on a limb and predict than many listeners will have a very hard time telling the two units apart during such a test. It's not that "bits is bits" or that all DACs sound the same, but that both units deliver such a high level of resolution and successfully pass so much of the original digital signal to their analog stages that differences are extremely subtle even in a high resolution nearfield listening environment.

Ergonomically the Bel Canto's volume control allows for much finer volume adjustments and the Dac3 responds and locks onto input changes far more rapidly then the Benchmark DAC1. The Bel Canto is considerably more visually striking and projects more of a high-end consumer component look and feel than the Benchmark DAC1, which has decidedly pedestrian pro audio cosmetics.

Pick One?
Given their difference in price, $1295 for the Benchmark verses $2495 for the Bel Canto, if you're on a budget the Benchmark DAC1 is an easy choice since it nearly equals the Bel Canto's e.One Dac3 sonics. But for the extra $1200 the Bel Canto does offer a superior level of ergonomic and visual elegance as well as a slightly more dynamically robust lower midrange. I could easily live with either component without feeling deprived, but if I had to choose without price being a consideration I'd go for the Bel Canto every time.

Coming Attractions
Next time The Nearfield will look at one of my favorite subjects – speakers. The Harbeth P3, Cabasse IO2, and Canton CD 220 will all get a thorough workout. So, till next time, keep enjoying your near-field music system.

Company Information
Bel Canto Design, Ltd.
221 North 1st Street
Minneapolis MN 55401

Voice: (612) 317-4550
Fax: (612) 359-9358
Website: www.belcantodesign.com

Benchmark Media Systems, Inc. 
5925 Court Street Road 
Syracuse, NY 13206

Voice: (315) 437-6300 
Fax: (315) 437-8119
E-mail: sales@benchmarkmedia.com
Website: www.benchmarkmedia.com