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™ 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 LEDs - 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 reduces hum and line-related interference
The DAC1 USB is a mastering-quality, 2-channel 96-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 Advanced USB™ 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 difficult 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 at 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 significant, non-musical digital distortion at audible levels.
Audio streamed via USB is subject to significant 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 amplifier. The HPA2™ is arguably the ultimate reference headphone amplifier. 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 View
- 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, 12.75UI 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 amplifier output impedance: 0.01 ohm
- Headphone amplifier output-level range at 0 dBFS into 60 ohm load: Off-to+21 dBu
- Headphone amplifier THD+N: -107 dB, 0.00045% with -3 dBFS input
