Anyone who has purchased a digital-to-analog converter (DAC) or DVD player during the last 10 years knows the prices for high-performance digital products have been steadily coming down. Four thousand dollars used to be the magic number needed to obtain a top-performing DAC. Then $2,000 DACs like the Wyred4Sound DAC-2 and Benchmark DAC2 made that price a "sweet spot" for high-performance DACs. Recently I've listened to a number of $1,000 DACs - such as the Lindemann USB-DAC 24/192 and NuForce DAC-100, with sonics that easily rival older and far more expensive DACs. Now Rotel is attempting to bring state-of-the-art digital performance to the under-$800 price range with its new $799 RDD-1580.
Designed to serve as a digital hub, the RDD-1580 has a multiplicity of inputs, including two RCA S/PDIF, two Toslink, and two USB inputs. One of the two USB inputs is located on the front panel and supports a digital signal from an iPhone, iPad, or iPod (it will also charge the connected iDevice). The USB connection on the rear panel supports USB 2.0 protocols and comes with a dedicated driver on a USB key for Windows PCs; Macs are plug-and-play for any PCM bit rate and format via USB up to 24/192. The Rotel RDD-1580 does not support DSD. In terms of analog outputs, the RDD-1580 has one pair of single-ended RCA and one pair of balanced XLR, both of which are always active.
The RDD-1580's physical footprint is only 1.75 inches high, 17 inches wide, and 12 inches deep. Available in either brushed silver or matte black, the front panel has a large on/off button on the extreme left, six source-selection buttons topped with blue LEDs in the center, and six sample/bit-rate indicators on the extreme right. An illuminated bright blue circle surrounds the on/off button. For users who find the blue circle of light too bright, Rotel supplies a little plastic ring you can place over the circle to reduce its brightness. The RDD-1580 comes with a nine-inch-long, wand-like remote control, which you can use to turn the RDD-1580 on and off and select a source. The remote also supports other Rotel devices, such as a CD player, with controls for play, stop, pause, fast-forward, and reverse. The remote is relatively large, with two-thirds of it being empty real estate. On the plus side, it's hard to lose, but all of its functions could have easily fit onto a credit card-sized remote.
Inside the RDD-1580 is a pair of Wolfson WM8749 DAC chips. By using one DAC for each channel, Rotel gets lower noise and distortion figures than by using a single chip for both. Rotel also developed its own custom digital filter array and output stage circuits for the RDD-1580. According to Rotel, "The carefully tuned analog section is another example of Rotel's award-winning Balanced Design approach in which specifications alone do not dictate which electronic parts are selected. Rather, extensive listening tests are carried out under controlled conditions to determine the optimal choices. During this time the entire circuit is carefully tuned to provide musically true signal reproduction ... After this, the entire circuit is tuned to extract the most sonically accurate signal possible." The power supply is also tightly regulated and uses a toroidal transformer, as well as special slit-foil capacitors to ensure greater operating stability. For its USB inputs, Rotel employs an asynchronous connection scheme to reduce digital jitter and clock-based distortions.
During the review period, the RDD-1580 worked with almost no glitches. My Mac's MIDI audio control panel immediately recognized the RDD-1580 when I connected a USB cable between the RDD-1580 and my MacBook Pro. All sample-rate options up to 24/192 were available. The front-panel USB connection worked with both my iPhone 5 and iPod Touch, with no issues playing or recharging the devices. The RDD-1580's remote control also worked without any issues, as did the front-control buttons and indicators.
The only ergonomic issue I experienced with the RDD-1580 was that a delay often occurred when I switched from the front-panel iDevice USB port to the rear-panel USB 2.0 port. Sometimes I had to switch back and forth more than once to get the RDD-1580 to begin passing a USB 2.0 signal. Also, whenever I switched from the front-panel USB to the rear panel USB 2.0, my Mac's iTunes playback software would go into pause mode. While not a big deal during normal use, if you want to try to compare a track playing through your portable iDevice with that same file being played back through your computer, the delay will make that comparison more difficult.
Click on over to Page 2 for the Performance, Downside, Competition and Comparison, and Conclusion . . .