The flagship Benchmark ADC1 USB, sadly now out of production. Thes don't come up for sale very often
Excellent condition, no major marks, perfectly functional
Super clean converter with up to 39 dB of clean adjustable gain
Can output multiple bitrates and sample rates simultaneously
Seller to pay $30 fo rinsured ground shipping anywhere in the USCheck my feedback and bid with confidence
From the Benchmark Site:

The ADC1 USB is a 2-channel 192-kHz 24-bit analog-to-digital audio converter with an unprecedented feature set. This converter was designed to consistently deliver reference quality conversion in 'real-world' conditions. It features Benchmark's jitter-immune UltraLock™ clock system and an extraordinary analog front-end.

DESIGNED, ASSEMBLED, AND TESTED IN THE USA

This Benchmark product was designed, assembled, and tested in the USA using USA and imported components. Most major components are made in USA.

Jitter-immune UltraLock™

The UltraLock™ system delivers consistent, high-quality conversion even when slaved to a poor quality external clock. The performance of the ADC1 USB will not degrade when slaved to an external clock - a claim very few converters can make. Enjoy the convenience of a clock input that automatically recognizes AES/EBU, S/PDIF, Word Clock, or Super Clock sources - all with the unsurpassed jitter immunity of Benchmark's UltraLock™ clock-isolation system.

Benchmark's Precision Analog Circuitry

Benchmark has a long tradition of building ultra-high performance analog circuits that are designed for maximum transparency. The ADC1 USB extends this tradition by pushing performance to the limits of today's technology. The analog front-end delivers low-noise low-distortion high-bandwidth performance over a wide gain range (45dB). Precise gain and calibration controls allow for accurate channel matching. The ADC1 captures precise imaging, subtle details, and difficult transients - all with stunning realism.

"The Benchmark ADC1’s sonic qualities are stunning; the converter has the ability to realistically reproduce all the fine inner detail and presence subtitles that only the best high-resolution converters can. Impressive. Put a set of these in your ProTools rig."

- John Gatski, Pro Audio Review

Intelligent Meters

The nine-segment dual-range, digital LED meters enable high-precision level monitoring. Meter response times are matched to the response of the human eye so that every peak is clearly visible. All metering is fully-digital and is not subject to calibration errors. A peak hold function allows an infinite hold to verify that an over has not occurred. Dual ranges allow signal presence monitoring, or precise headroom indication. The meters even use an upsampling technique to detect and display inter-sample peak overloads. This upsampled metering warns of potential overloads that may not be detected by conventional digital meters.

Flexible Digital Outputs

The ADC1 USB has a total of 5 digital outputs (1-XLR, 2-coax, 1-optical, and 1-USB). These can operate simultaneously at up to three independent sample rates. One of the coaxial outputs can be configured for 16-bit TPDF dithered output. This unique flexibility allows simultaneous recording to a CDR, while recording high-resolution to a digital recorder and a DAW. For example the CDR may operate at 44.1/16 while the DAW operates at 88.2/24 while the digital recorder operates at 192/24. Backup and/or reference recordings can be created with ease while high-resolution outputs are fed to primary recording devices. The optical output supports AES or ADAT formats at resolutions up to 192/24. In ADAT mode, high sample rates are supported using SMUX2 and SMUX4.

Benchmark's AdvancedUSB

Benchmark's AdvancedUSB™ solution provides a bit-transparent computer interface that is capable of streaming at rates up to 96 kHz/24-bit without installing any drivers. This reduces CPU loading, eliminates driver compatibility issues, and greatly improves the reliability of the data transfer. Benchmark's unique driverless AdvancedUSB™ solution is compatible with Mac OSX and Windows 2000, XP, and Vista. Benchmark's UltraLock™ clock system insures the audio will never be contaminated with jitter-induced artifacts from a poor-quality computer-based clock. With the Benchmark ADC1, the performance of the USB interface matches the quality of the AES and ADAT interfaces. The convenience of a direct computer interface no longer comes with a performance penalty!

Consistent Performance

Often specifications only indicate how a product will perform under the most optimal conditions. The ADC1 USB is designed to deliver consistent performance - even in adverse conditions. The ADC1 USB is fully specified at all gain settings, all sample rates, through all digital outputs, and even when locked to a high-jitter clock signal. This performance insures reliable and predictable results in the 'real world'.

"Benchmark's versatile and full-featured ADC1 USB both measures superbly well and produces digital files that sound equally superb."
- John Atkinson, Stereophile

Specifications

SNR – A-Weighted, 0 dBFS = +16 to +29 dBu

121 dB

SNR – Unweighted, 0 dBFS = +16 to +29 dBu

119 dB

SNR – A-Weighted at max gain, 0 dBFS = -10 dBv

117 dB

THD+N, 1 kHz at –1 dBFS

-102 dBFS, -101 dB, 0.00089%

THD+N, 1 kHz at –3 dBFS

-107 dBFS, -104 dB, 0.00063%

THD+N, 20 to 20 kHz test tone at –3 dBFS

-106 dBFS, -103 dB, 0.00071%

Frequency Response at Fs=192 kHz

-3 dB, +0 dB, 2 Hz to 94 kHz

+/- 0.01 dB, 20 Hz to 20 kHz