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Thursday, December 31, 2015

Home Recording Studio Review!
Benchmark DAC2-DX D/A Converter
"AES/EBU Input, Dual-Buss Output Added"

©Everything Audio Network

Brevis...
Price: $1,995
Likes: AES/EBU, dual buss out
Dislikes: loses the analog input
Wow Factor: refining the DAC2 
Info: Benchmark DAC2-DX

by John Gatski
  Ever since Benchmark released the DAC2 Series a few years ago, the D/A’s measured performance, ultra-accurate smooth ESS-chip audio delivery has made, it, er, the Benchmark of D/A converters. Every DAC I get in for review, I always compare to the Benchmark.
  Now, the company has several DAC2 models — from line level-only models to versions without remote control. The new DAC2-DX corrects an omission from the original DAC2-HGC introduction: it adds AES/EBU via XLR, a feature we have not seen on a Benchmark DAC since the DAC1 Series. The DAC2-DX also has a few other new features, including dual stereo buss output — with the ability to control each output’s volume separately.

Features
  The DAC2-DX, priced at $1,995 with remote ($1,895 without remote), replaces the DAC2-D I reviewed three years ago, which had 2 SPDIF, 2 TOSlink and USB digital inputs. The DAC2-DX retains all of these inputs and adds an AEX/EBU XLR input, all capable of 24/192 audio. To make room for the AES/EBU connector, the DAC2-DX loses the RCA unbalanced inputs (of the DAC2-HGC and L models). It still has two sets of RCA unbalanced outputs, as well as the balanced XLR analog output. The DSD input is via USB.
  The DAC2-DX still uses the same 8-channel 32-bit Sabre32 ESS9018 D/A converter. Four balanced outputs are summed in balanced low-impedance I/V converters to form each of the two balanced output channels. National Semiconductor LME49860 op-amps (which can easily handle low impedance loads) are used throughout the audio path. An Alps motorized gain control is used to control the volume.


DAC2-DX can handle any digital source


  Digital processing includes a Burr-Brown SRC4392 Digital Audio transceiver, and a Xilinx FPGA running custom Benchmark firmware. The DSP functions include Benchmark's UltraLock2(TM) jitter attenuation system, asynchronous upsampling, automatic de-emphasis, PCM and DSD filters, DoP decoding (for DSD playback), word-length detection and sample rate detection. The DAC2 Series uses distributed voltage regulation. Each critical circuit has dedicated low-noise voltage regulators. As per Benchmark's typical high-grade build quality, the circuit board has six layers of copper and includes 3-dimensional shielding for critical signals.
  The DAC2 Series is one of the few DACs that displays word length and sample rate, a feature I always push with DAC manufacturers. The new DAC2 also supports native DSD via DoP, and contains a digital pass through by simply pulling an internal jumper for one of the coax inputs.

The primary difference from other DAC2 models is the inclusion of balanced XLR AES/EBU input which makes it more compatible with professional equipment and high-end audiophile gear, and the dual stereo buss output.

  As mentioned, the primary difference from other DAC2 models is the inclusion of balanced XLR AES/EBU input which makes it more compatible with professional equipment and high-end audiophile gear, and the dual stereo buss output. The dual buss system allows you to independently control the level of headphone amp and provide a fixed or variable level through the XLR or RCA unbalanced analog outputs. Therefore, in a pro setting, output audio can be directed to say the control room to powered speakers for monitoring a mastering session, as well as to second room. I used the DAC2-DX’s outputs to feed a second headphone amp and set of powered KRK speakers mounted near my console meter bridge.
  The front panel features familiar Benchmark controls. From left to right are: the power, mute, dim, and input-select buttons and LED indicators. Unlike the Dim feature on the other DAC2 models however, the DAC2-DX’s Dim function reduces volume immediately by a fixed 20dB. This is a very useful feature to quickly reduce volume without fully muting the output. The rear-panel inputs include USB, D1 and D2 (TOSlink), D3 (AES EBU), and D4 and 5 (SPDIF coaxial). The analog output is via a set of XLR balanced connections or the two sets of RCA unbalanced connections.
  The 24- and 16-bit indicators show the incoming word length. The sample rates are shown by the 44.1 kHz and 48 kHz LEDs, along with the 4X and 2X, Hence, 96 kHz is shown as 48 kHz and 2x. 192 kHz sample rate is seen as 48 kHz x 4. The Alps volume control and twin headphone outputs round out the front panel.

The audition
  Though tailored more for high-end pro and audiophile systems with AES/EBU connectivity, the DAC2-DX sounds just like the other DAC2s: intricately detailed and smooth, courtesy of its exceptional implementation of the high-end ESS Sabre DAC chip and ability to accurately reproduce inter-sample peaks (also known as inter-sample “overs”) without clipping and without DSP overload errors. The dynamics of a Benchmark DAC2 Series converter is hard to match.
  The DAC2-DX’s headphone amp is robust enough to handle power hungry AKG phones, such as the brilliant AKG-K803, or any ‘phone set you want to connect to it. I also like the performance of the Oppo PM-2 planar magnetic phone and Shure SRH-1840, both open back.
  For testing in my home recording rig, I connected the DAC2-DX to the TASCAM DA-3000 24/192-DSD recorder/player’s AES/EBU output. It worked perfectly. To listen to the KRK powered speakers, I fed the XLR balanced line out at fixed level to a dedicated mixer preamp, which controlled level of my KRK powered studio monitors.


DAC2-DX retains high-end HP amp, word-length status

    First, I used the headphone jack for quality checking of a 24/192 acoustic guitar recording that I had done using the DA-3000. I then went to the speakers to sit down for repeat listening checking the mix, balance, etc. The sound was transparent, open, not too bright, yet you could hear all the intricate depth of those finger-picked string harmonics. Just what I expect from a Benchmark: one of the most accurate D/A converters out there!
  I also connected the DAC2-DX to my Macbook Pro’s USB port for monitoring duties via Twist Wave editing program. The computer recognized the DAC, and I got busy with various QC and playlist editing sessions, etc. I really appreciate Benchmark’s word-length indicator. Sometimes in Mac, when switching between audio programs, the Mac audio system will sometimes switch from 24-bit to 16-bit by itself. If that happens, the DAC2 shows me with its LED indicators, and I manually switch (mouse click) the OS back to 24 bit.

The verdict
  If you like a clean, transparent, yet smooth and detailed D/A converter for your home pro (or larger separate pro facility) or hobbyist studio, the DAC2-DX  should be on your short list of DACs to consider. And it now has the right amount of features, including AES/EBU digital input and dual buss routing. I cannot emphasize enough the DAC2's sound quality. If your only experience has been with the old DAC1 Series, you are in for a treat. The DAC2 blows it away in terms of listenability. Significantly smoother, especially with Pop music. Like the DAC2-HGC, the DAC2-DX receives our Stellar Sound Award and an 2015 EAN Product of The Year Award nod in the home recording studio category.




  John Gatski has been evaluating consumer, audiophile, home cinema and professional audio gear since 1988. In 1995, he created Pro Audio Review, and he has written for Audio, Laserviews, Enjoy The Music, The Audiophile Voice, High Performance Review, Radio World and TV Technology. Everything Audio Network is based in Kensington, Md. Articles on this site are the copyright of the ©Everything Audio Network. Any unauthorized use, via print or Internet, without written permission is prohibited. John Gatski can be reached via everything.audio@verizon.net

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