Benchmark DAC1 D/A converter.

Manufacturer: Benchmark Media Systems Inc., 5925 Court St. Rd., Syracuse, NY 13206; www.BenchmarkMedia.com; 315-437-6300

Price: $975

Source: Manufacturer loan

Reviewer: James T. Frane

Compact disc players read a digital signal from a CD and translate it to a listenable (analog) format. Benchmark Media System's DAC1 is an add-on unit designed improve the conversion quality beyond that of a built-in converter. It can be added to any digital piece of equipment, such as a DVD player, and has sufficient signal strength to drive either a preamp or a power amp. The DAC1 is small, measuring 9.5-inches wide (half the width of a standard rack) x 8.5-inches deep x 1.725-inches high, and weighs 3.5 lb. Its black enclosure has rack mount extensions and holes. On the front, from left to right are:

1) A vertical stack of three very bright LEDs. In use, I found the LEDs too bright for my eyes, and turned the unit so it faced to the side:

* The uppermost LED is blue and designates when there is power to the unit;

* Next is a red LED that indicates an error, and may be triggered by a signal out of the sample range, no digital input signal, or a digital input signal that is too low;

* The third LED, also red, indicates that the digital signal is a type that cannot be decoded by the DAC1, such as Dolby AC3.

2) To the right of the three LEDs is a three-position "Input Selector" toggle switch--from top to bottom, the positions are coaxial, XLR, optical;

3) Next are two 1/4-inch headphone jacks;

4) The last item on the front is a variable gain control for the headphone jack output level. This control can be used for the XLR and RCA analog outputs, when the output level switch on the unit's back is in "variable" position.

On the gold-colored back panel, from left to right, are:

1) Output RCA phono jacks;

2) An output level switch to select calibrated or variable;

3) Left-right balanced outputs;

4) Coax input connectors;

5) Optical jack input connector;

6) XLR input connector;

7) Power cord connector.

Benchmark's 39-page instruction manual is extremely thorough with photos, specifications, detail control descriptions, certificate of conformity to specific test standards, and performance curves. The unit carries a 5-year repair warranty.

One of the features of the 192 kHz DAC1 is Benchmark's UltraLock technology, which is a 24-bit analog conversion system for jitter elimination. With this approach, the converter over-sampling ratio is precisely varied to achieve the proper reference clock phase relationship, preventing interface jitter from degrading the conversion.

Associated Equipment: Bryston BP25 preamp and Parasound HCA-1000A power amplifier with Thiel CS 2.4 speakers. Sources were a Sony CDP-XA20ES CD player with the Thiels and a Samsung DVD-611 DVD/ CD player with Mach One model M-Two 2-way speakers on a shelf and two Cambridge Soundworks Ensemble low frequency units driven by a Carver TFM-55X power amp with Carver CT-26v preamp-tuner. The M-Twos were run full range. Speaker connections were via Mach I twisted pair cables to the Thiels with Kimber 4PR cables to the Mach Ones. Interconnect cables were by Vampire, WireWorld, and Gotham.

I connected the Sony CD player two ways simultaneously: 1) the Sony's digital output through the DAC 1 to the preamp; and 2) the Sony's analog output to the preamp. With this setup, I was able to switch back and forth between the sound of the DAC1 output and the CD player's built-in DAC output. A sound level meter was used to match the outputs, so there was no identifiable difference in volume between them. In both blind and double blind switching, I noted no difference between the Sony built-in DAC and the Benchmark DAC1 sound. I used the Digital Recordings CD-CHECK test disc (DR 2002) to test error correction. The results showed it was no difference with and without the DAC1. There are five check levels on the CD-CHECK disc, each successively more difficult to play, as the error magnitude increases. The instructions accompanying the disc state that all CD players should pass level one, and that the best will pass all five levels without sound alteration or distortion: "Each track has a smooth continuous tone if errors are corrected. Any clicks, interruptions, skipping, or looping indicate failure of a check level." The Sony DAC and the DAC1 passed the first four tests, but both reproduced level five with a steady stream of clicks. Music sounded the same with the Sony built-in DAC and the Benchmark DAC1. This indicates to me that the Sony works quite well.

To test the DAC1 with the Samsung DVD-611 player, I used the same optical cable from the Sony test and matched the output levels. The Samsung DVD/CD player did not do as well with the CD-CHECK disc as did the Sony: There were a few clicks on cuts 2 and 3, more on 4, and a steady stream on 5. Adding the DAC1 to the Samsung made no improvement in the performance with this test disc. The fault was apparently within the Samsung circuitry upstream of the digital-out connection feeding the DAC1. However, there were noticeable improvements with music when the Samsung digital output was decoded by the DAC1 (despite the CD-CHECK results).

Among the CDs I used for listening tests with both setups were The Legendary Casals (EMI 7243 5 67008 2 6), Diana Krall's Live in Paris (Verve 440 065 109-2), Bill Evans's Jazz "Round Midnight (Verve 314 517 773-2), and Dave Brubeck's Jazz Impressions of New York (Columbia CK 46189). Brubeck's "Theme from Mr. Broadway" gained spaciousness and depth, as did Ms. Krall's "I Love Being Here with You." With DAC1 added to the Samsung, Casals's cello gained depth and texture. Depth, width and openness improved on The Evans Trio's "Turn Out The Stars." In each case, the degree of improvement was welcome and worthwhile. Ms. Krall's voice had more detail and sounded more realistic.

The sound was significantly better than the Samsung's on-board digital-to-analog converter. However, I could not discern a difference when the DAC1 was used in place of the Sony's digital-to-analog converter. It appears that the degree of improvement the DAC1 can make will vary with the quality of a digital component's built-in DAC. Altogether, the Benchmark DAC1 is solidly built, nicely finished and easy to use. A cautionary note: You might want to arrange with your dealer for a trial of the DAC1 to see how it works with your system. If it makes an improvement, I think you'll want to keep it.--JTF