BENCHMARK
DAC1 USB STEREO 24-BIT 192 KHZ D/A CONVERTER
Features
• Four digital inputs: USB, XLR balanced,
BNC coaxial, and TOSLINK optical
• AdvancedUSB™ interface for native
96-kHz / 24-bit USB audio
• Compatible with Windows Vista/XP/2000
and Mac OS X without driver installation
• Benchmark’s phase-accurate UltraLock™
technology provides total jitter immunity
• Four stereo outputs: XLR balanced,
RCA unbalanced, and two headphone jacks
• Front panel volume control eliminates the
need for a playback-system pre-amplifier
• Built-in HPA2™ 0-W, high-output
headphone amplifier (two 1/4” outputs)
• Selectable gain-range for headphone
amplifier to match headphone sensitivity
• Left-most headphone jack mutes XLR and
RCA outputs (this feature is defeatable)
• “Calibrated/Variable” switch determines
gain control for main analog outputs
• Front-panel gain control of all analog
outputs (in “Variable” mode)
• Front-panel gain control of headphone
outputs only (in “Calibrated” mode)
• Rear-panel trim-pots control gain of XLR
and RCA outputs (in “Calibrated” mode)
• Selectable, low-impedance attenuators
(0, 10, 20, or 30 db) on XLR outputs
• Status LED’s - display input selection and
error conditions
• Automatic “Standby Mode” - active after
15 seconds of loss of digital input signal
• Automatic wake-up from “Standby Mode”
• Reliable and consistent performance
under adverse operating conditions
• 115 V, 230 V, 50-60 Hz international power
supply with very wide operating range
• Low radiation toroidal power transformer
significantly reduces hum and line-related
interference
The DAC1 USB is a mastering-quality, 2-channel 192-kHz 24-bit digital-to-analog audio
converter. Engineers and audiophiles have grown to rely on Benchmark for critical digital
audio conversion for more then 10 years. They are consistently finding themselves
engaged in the music in a way that is rarely achieved with digital converters.
Benchmark converters perform with unprecedented sonic purity through intelligent
engineering–eliminating digital distortion artifacts and achieving a pristine analog
delivery path. The DAC1 USB continues this tradition of excellence.
Preserving the Classic DAC1 Heritage
The superior performance of the award-winning DAC1 has made it the ‘Benchmark’ of
D-to-A converters. The DAC1 USB preserves the exact topology of the audio path of the
classic DAC1, while adding some of the most frequently requested features.
The DAC1 and DAC1 USB both include Benchmark’s jitter-immune UltraLock™ clock
system and Benchmark’s 0-ohm HPA2™ headphone amplifier. The DAC1 USB features
Benchmark’s AdvancedUSB™ technology to ensure bit-transparent, high-resolution
playback directly from your computer. The DAC1 USB also includes a ‘mains-mute’
function that automatically mutes the main outputs upon insertion of a headphone plug.
Other features that are exclusive to the DAC1 USB include selectable headphone gain
ranges, an automatic standby feature, and a high-current output stage designed to drive
even the most diffi cult loads.
Jitter-Immune UltraLock™ Clock System
Benchmark’s proprietary UltraLock™ clock system achieves an unprecedented immunity
to jitter. Many modern (and expensive) converters suffer from signifi cant jitter-induced
distortion. If jitter is not effectively addressed, a converter will generate non-musical
sideband tones and digital distortion. Benchmark’s highly-regarded UltraLock™ clock
system ensures that jitter is never a problem, even under extreme conditions.
Even in the presence of extremely high input jitter, no jitter-induced artifacts can be
detected on the outputs of the DAC1 USB (using state-of-the-art testing equipment by
Audio Precision). UltraLock™ will block more than 12.5 UI of jitter (@ 1 kHz).
With the UltraLock™ clock system, the D/A conversion-clock in the DAC1 USB is totally
isolated from the clock of the digital audio source. The UltraLock™ clock system easily
outperforms most well-designed two-stage PLL designs.
The bottom line is this: Benchmark converters will consistently and faithfully deliver
truthful audio without jitter-induced artifacts, no matter what variables are present.
AdvancedUSB™ Audio Technology
The USB interface of the DAC1 USB operates with Benchmark’s unique AdvancedUSB™
technology. Unlike many USB equipped D/A converters, Benchmark’s AdvancedUSB™
technology supports 24-bit audio at sample rates up to 96 kHz without the installation of
any drivers or other special software. Benchmark’s UltraLock™ clock system isolates the
converter from the high levels of jitter that are found on USB interfaces. AdvancedUSB™
responds automatically to sample-rate changes to bypass the operating system’s
sample-rate conversion. The DAC1 USB achieves transparent, audiophile-quality
playback through a true plug-and-play solution.
It is very important to have a 24-bit USB path, even for 16-bit playback, because digital
volume controls and other DSP functions can increase 16-bit audio to 24 bits. If a
16-bit USB interface is used, up to 8 bits of each digital audio sample will be truncated
- resulting in signifi cant, non-musical digital distortion at audible levels.
Audio streamed via USB is subject to signifi cant amounts of jitter. The AdvancedUSB™
interface utilizes the UltraLock™ clock system. Consequently, the performance of the
USB input is equal to the performance of the other inputs, regardless of the jitter present.
The DAC1 USB is natively compatible with Windows Vista/XP/2000 and Mac OS X. As a
native device, there are no drivers or other software required to install or configure.
HPA2™ Headphone Amplifier
The DAC1 USB includes the HPA2™–Benchmark’s signature high-current, 0-Ohm
headphone amplifi er. The HPA2™ is arguably the ultimate reference headphone amplifi er.
It will deliver the full rated performance of the DAC1 to the headphones. The HPA2™
maintains less than 0.0003% THD+N under a full load from two sets of headphones. The
DAC1 USB has two 1/4” headphone jacks on the front panel.
rear viewSPECIFICATIONS
• THD+N: -107 dB, 0.00045%
(w/ -3 dBFS input)
• SNR–A-weighted: 116 dB
(w/ 0 dBFS = +20 to +29 dBu)
• Maximum Amplitude of Jitter-Induced
Sidebands (10-kHz– 0 dBFS test tone, 12.75
UI sinusoidal jitter at 1 kHz):< -141 dB
• Maximum Amplitude of AC line-related
Hum & Noise: < -126 dB
• Input Sample Frequency Range:
28 to 195 kHz
• Headphone amp output
impedance: 0.01 ohm
• Headphone amp output-level range
(@ 0 dBFS into 60 ohm load): Off-to+21 dBu
• Headphone amp THD+N:
-107 dB, 0.00045% (w/ -3 dBFS input)
