Benchmark DAC2 HGC D/A processor/headphone amplifier
In 2007, I spent time with Bel Canto Design's e.One DAC3 D/A processor. In his review of the DAC3 in the November 2007 issue, John Atkinson quoted my comparison of it with the Benchmark DAC1, which I called "the Swiss army knife of audio" and "one of the only future-proof source components you can buy these days."
Sure enough, in 2013, the standalone DAC-preamp has become an integral part of the audiophile world, and no company has led the way to the high-quality DAC/preamp/headphone amp as confidently as has Benchmark Media. I bought my original Benchmark DAC1 ($995) because I was an up-and-coming musician who didn't have a ton of cash but who knew what high-quality audio was supposed to sound like. I produced recording sessions, and needed something that could play high-resolution files through my headphones. I also wanted a component that could play data from a silver disc and work with my computerwhich I saw as the future of the digital front end.
Keeping up with the times and the needs of the digital marketplace, Benchmark has steadily improved and added to its original model, the DAC1. They released the DAC1 PRE, which added an analog preamp, then the DAC1 USB and the DAC1 HDR, which improved the volume control and used higher-quality op-amps. I found the DAC1 HDR to offer slightly better, smoother sound than my DAC1. So when I had the chance to listen to Benchmark's new DAC2 HGC, I was very curious to hear where it fit in Benchmark's impressive lineage.
The Benchmark DAC2 HGC ($1995) has a number of features not included in its older siblings. First, the front panel boasts sample-rate and word-length displays. These are invaluable tools, especially when your digital front end is a computer and you want to know if you've configured your audio settings correctly to play hi-rez files. While I can usually hear when a hi-rez file is being incorrectly truncated or decimated, checking the LEDs on the DAC2's faceplate reassured me that I was indeed hearing what I was supposed to be hearing.
The front panel also has buttons for Power, Dim/Mute, Input, and Polarity, a motorized Alps volume pot, and two ½" headphone jacks. Except for the last, all of these functions can also be handled via the included remote control, which I found elegantly simple in design, layout, and function.
The DAC2 HGC has five digital inputs: USB, two optical, and two RCA coaxial. The USB input works in asynchronous mode and will operate in either USB 1.1 or USB 2.0 modes. If you play only 24-bit/96kHz files via USB, no extra drivers are needed. To play DSD or 192kHz files, a downloadable driver is provided for Windows computers, and the DAC2 must be set to USB 2.0 mode. While the DAC2 HGC has a lot of inputs, I miss the DAC1's balanced AES/EBU input and its BNC connectors for the S/PDIF inputs, all of which I used. The DAC2 has two pairs of analog inputs, whose signals remain wholly in the analog domain from input to output (more on that later). These lead to three analog outputs, one balanced and two single-ended. And one of the coaxial digital inputs can be configured to act as a digital pass-through.
The DAC2 HGC offers two new features that should improve sound quality over Benchmark's older DACs. First, it converts digital signals with four 32-bit ESS Sabre DACs run in balanced configuration. Benchmark claims that the DAC2 HGC is a full 10dB quieter than the DAC1. The DAC2's digital processing is also claimed to have 3.5dB of digital headroom when fed a signal of 0dBFS. With today's standard practice of overloud mastering, this much headroom should ensure that no digital clipping occurs, and that the filter runs more linearly when fed high-level inputs.
Also new in the DAC2 is Benchmark's Hybrid Gain Control (HGC), for volume attenuation. The HGC grew out of Benchmark's experience with their HDR volume control included in the DAC1 HDR. As I understand it, the DAC2's volume control combines active analog gain control and passive low-impedance attenuators in the analog realm with a 32-bit digital DSP gain control for digital signals. Unlike many DAC-preamps, the DAC2 HGC keeps all analog inputs in the analog domain, instead of relying on digital conversion at both input and output. Analog purists, rejoice!
Like the Benchmark DACs before it, the DAC2 HGC is half a rack unit wide and comes in a black or silver case. Optional rack mounts are available. The layout is very clear and organized, the styling professionally oriented. The fit and finish were great, and the feel of the volume control was solid and silkybut the DAC2 lacks any pretention of being audio jewelry.
I began listening to the DAC2 HGC using my Sennheiser HD600 headphones and Hewlett-Packard EliteBook 8570p laptop computer. The HP has an Intel i7 chip, runs at 2.90GHz with 8GB of RAM, and runs Windows 7 Professional (64-bit). For all of my critical listening I used JRiver's Media Center 18, which I've found offers the best sound from my computer. The DAC2 was connected to the HP via DH Labs' USB cable, which sounds (and looks) lovely.
The DAC2 HGC doesn't use a separate audio driver to interface with the computerit really is plug-and-play in USB1.1 mode. [Benchmark does supply a driver package, including ASIO support, for operation in USB2.0 mode.Ed.]. However, when using a program like Media Center, having a dedicated ASIO driver comes in handy when I try to bypass as much of my laptop's audio circuits as possible. After going through Benchmark's checklist in the comprehensive manual of how to create the best settings for using the DAC2 with Windows 7, I was still unable to entirely bypass my laptop's volume control. Benchmark suggests that users who set their computer's volume level to "100" should get bit-transparent data, but I'm always leery when I can't bypass all of my computer's audio functions. By contrast, when I use the $795 Centrance DACmini D/A converter, which I reviewed in December 2011, I have the option to either plug-and-play or use their optional ASIO driver in Media Player. When I select ASIO, I can easily get my computer's audio functions out of the signal path. With the Benchmark, I was never quite sure I had. However, I was sure of the bit depth and sample rate I was sending to the DAC2: I could read it on the Benchmark's LED display.
Headphone Sound Quality
A hi-rez download of Daft Punk's Random Access Memories (24/88.2 FLAC files, Columbia/HDtracks) provided fantastic listening via my Sennheiser HD600s. The tasty bass playing on the robot's "Give Life Back to Music" was full, controlled, solid, and driven, and Nile Rodgers's classic Stratocaster rhythm-guitar work really shone through the DAC2. What would normally be merely a pop song's background rhythm guitar was brought to the fore by the DAC2, allowing me to appreciate the subtle voicings and strumming patterns Rodgers chose for this groove. Hearing this track through the DAC2 made me appreciate why Nile Rodgers is the man.
Part of what made it easy to pick out Rodgers's rhythm-guitar work was the DAC2's ability to offer wonderful image size and separation via headphones, while still giving each instrument the proper solidity and scale in the mix. I think that partly comes from a low level of self-noise, which the DAC2 certainly seemed to have. But from treble to bass, the DAC2's sound through headphones was also very dynamic and even, highlighting nothing but missing nothing.