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Unmask Your Audio with the DAC1 USB
"Very Highly Recommended," Says Stereophile
Benchmark's DAC1 USB is a reference-quality, 2-channel 192-kHz 24-bit digital-to-analog audio converter featuring Benchmark's Advanced USB Audio technology, UltraLock clock system, and HPA2 headphone amplifier.
The pristine audio path of the award-winning DAC1 has made it the Benchmark of stand-alone D/A converters. It was a Stereophile Product of the Year for 2004. "You can't find much more in the way of a high-end audio bargain than the Benchmark DAC1," raved the magazine.
"A Superb Sounding Device," Reports Stereophile
The DAC1 USB looks sounds and measures the same as the DAC1 with added benefits of convenience, flexibility, and performance.
In the January 2008 issue of Stereophile, John Atkinson reports, "Used via USB from my Mac mini and from its conventional data inputs, the DAC1 USB is a superb-sounding device."
And what about the built-in headphone amplifier? "The fact that it has an excellent-sounding headphone output with two choices of maximum gain makes it a bargain," Atkinson continues. "Very highly recommended."
Advanced USB Audio Technology
The DAC1 USB includes a unique USB input with bit-transparent native 96 / 24 capability, a programmable mute function, programmable headphone gain range, automatic standby / resume, and a high-current output stage designed to drive long cables or low-impedance loads, such as high-end power-amps. A true plug-and-play solution, the DAC1 USB begins playback immediately after the unit is connected to a USB port for the first time.
Bit-Transparent Digital Audio Path
A digital audio path can be tested to determine if the digital data is being modified or distorted in any way. This is done by sending a random sequence of bits through the path, and comparing the resulting sequence with the original sequence. If the resulting sequence is identical to the original, the path is 'bit-transparent'. Benchmark's USB technology is the first native USB solution capable of streaming 96 kHz, 24-bit audio with full 'bit-transparency'.
The 'Driverless' USB Solution
Until now, high-resolution USB audio devices required 'custom' drivers. These drivers may compromise the stability of the operating system. They also usually consume more system resources (memory and CPU) than native solutions and fail to deliver bit-transparent audio. The problem with native USB audio devices has been their inability to stream audio at sample-rates over 48 kHz and at word-lengths over 16-bits.
The DAC 1 USB does not require driver installation. When connected to a USB port on a computer running Windows® 2000, XP, Vista, or Mac OSX, the computer will instantaneously recognize the Benchmark USB device and instantly route any audio to it. Unlike all previous driverless USB audio interfaces, Benchmark's Advanced USB Audio technology supports sample rates up to 96 kHz and word lengths up to 24-bits.
In addition to the USB interface, the Benchmark includes coaxial, XLR, and optical digital inputs.*
Jitter-Immune UltraLock
The Benchmark UltraLock system is nearly 100% jitter immune. The D/A conversion clock is totally isolated from the input digital audio clock in a topology that outperforms two-stage PLL designs.
Any signal that can be decoded by the USB or AES/EBU receivers will be reproduced without the addition of any measurable jitter artifacts. The AES/EBU receiver IC has been selected for its ability to accurately recover data in the presence of very high jitter levels.
Built-in Headphone Amplifier
Two 1/4" headphone jacks are driven by the HPA2, Benchmark's signature high-current headphone amplifier. The left-hand headphone jack includes a switch that mutes the XLR and RCA analog outputs when a headphone plug is inserted. This mute feature can be disabled with internal jumpers.
The front-panel volume control sets the output level of the headphone jacks. It can also be used to control the output level of the balanced XLR and unbalanced RCA analog outputs. A rear-panel switch selects Variable or Calibrated output levels, respectively enabling or disabling the front- panel volume control.
Direct Interfacing to Power Amplifiers
The DAC1 USB can interface directly to power amps and powered studio monitors in order to provide the cleanest and shortest path from the digital source to the monitor output. This often results in a substantial improvement in sound quality. New high-current output drivers can 300-Ohm loads without an increase in distortion. They are also well suited for driving long cables or high-capacitance loads.
'Audio-Always' Design Philosophy
The DAC1 USB is designed to perform gracefully in the presence of errors and interruptions at the digital audio inputs. A soft mute circuit eliminates pops when a digital signal is applied. Power management circuitry controls the muting and resetting of all digital circuits upon removal and application of power.
The DAC1 USB will operate even when sample rate status bits are set incorrectly. Sample rate is determined by measuring the incoming signal. Lack of sample rate status bits or incorrectly set status bits will not cause loss of audio.
Low-Noise Internal Power Supply
The internal power supply supports all international voltages and has generous margins for over and under voltage conditions. It has excellent immunity to noise on the AC line and no external AC filtering is required.
*Note: Effective with all orders shipped after 2/1/12, the optical input connectors (Toslink) of all Benchmark DACs will be limited to 24/96. In the past, the optical receivers would accept up to 24/192. However, Toshiba, maker of the Toslink connector, no longer will manufacture a connector with this capability. There are no other suppliers. | 
