DACs

Wyred4Sound DAC-2 AND STI-500 Integrated Stereo Amplifier

ARTICLE INDEX

Design

The first thing that I noticed about the DAC-2 is that it's very large in size compared to most DAC's. The reason for this is that it uses many of the same case components as the monoblock amplifiers from Wyred4Sound, allowing them to stock fewer different parts for assembly and shipping, and lowering the costs associated with manufacturing the component. I wouldn't have minded the DAC-2 being a little smaller while in use as a desktop amp, but I'd rather have the savings passed on to me than to have a smaller, custom case.

One key feature to note with the DAC-2 is that is uses an asynchronous USB connection instead of the far more common synchronous method. In a typical synchronous connection, the DAC and computer will share a clock signal for the transfer of data over USB, which causes multiple issues. First, the speed of the USB bus isn't a multiple of the common data rates for audio, so you can't send uniform data packets at a constant interval. Second, the clocks in computers are typically very bad and subject to drift. This isn't as easy to notice on a day-to-day basis now, as most computers check the official time over the Internet and reset their clocks daily, but if you are relying on that clock for the precise transmission of thousands of packets a second, then those timing errors can show up quickly.

By using asynchronous USB the DAC-2 can get around these issues. Instead of sharing a clock, the DAC-2 uses its internal clock to keep the flow of data precise. If it starts to run low in its internal buffer, it sends a message to the computer to speed up the flow of data by a certain amount, and if it starts to receive too much data than it lets the computer know how much to slow down. This lets the DAC-2 receive the audio data at the correct rate, and reassemble them and use it's far more accurate internal clock to keep jitter much lower than on a synchronous USB connection. People might argue over how much jitter can affect the audio signal and how easily you can hear it's effects, but I think everyone will agree that keeping the level of jitter as low as possible is a good idea.

The connection on the DAC-2 that probably causes the most confusion is the HDMI port that is labeled as I2S. Whereas standard digital connections such as SPDIF carry the data with the clock signal inserted, I2S keeps the data and word clocks on separate signal paths, helping to greatly reduce jitter once again. The first appearance of using HDMI for an I2S signal was with the PS Audio Perfect Wave components. Wyred4Sound is using the same specifications in their DAC-2 so that you could hook up the PS Audio Perfect Wave Transport by HDMI and you would have an I2S digital connection between the two devices. Wyred4Sound is also working to add I2S outputs to existing players, starting with the Oppo BDP-83 so people that want to use their player as a high quality transport can do so.

Everything about the build of the DAC-2 really says quality. It arrived in perfect condition, double boxed, with good foam padding that will certainly survive multiple trips without an issue. The case itself is very solid, with nearly 20 screws keeping it in place. The connectors are all high quality, from the Neutrik XLR's to the gold plated RCA jacks that are firmly attached to the back plate with no wiggle at all. The front is kept very clean, with a VFD display, three small buttons for control and an IR sensor for the remote. Available in either silver or black, the DAC-2 might have a more utilitarian look than some other pieces of gear out there, but it's built with an industrial toughness and is as solid as anything I've seen recently.

The STI-500 came packed just as securely as the DAC-2, and built with the same high-quality components. The case is incredibly solid, with a 1/2" machined front panel, a Neutrik XLR input, the high quality, gold plated RCA jacks, high quality binding posts, the same VFD as the DAC-2, and a large volume control that also functions as a power toggle. Compared to a receiver that is in the same price range, the STI-500 was far more solidly built, with a bit of an industrial feel to it, but in the way that everything is designed around peak performance

Features that are present on the STI-500 include a 12V input and 12V output trigger, an optional pre-out and line in (for using an external crossover or room correction system, such as DEQX, with the STI), and a home theater bypass mode. This enables you to use the STI in a home theater setup quite easily, as long as your receiver or processor has a 12V trigger. When you setup the STI you can designate an input as the HT Bypass input, and run the Left and Right line outputs from your receiver to the STI, then connect the STI to your front speakers. When you turn on the receiver for a multichannel soundtrack, the 12V trigger will turn on the STI, set it to HT bypass mode, and disable all gain on the STI so that it strictly functions as a Class D amp for the front speakers.

When you wish to use an analog stereo source, you can run those components directly through the STI, letting you keep your receiver, processor, multichannel amp, and all other associated gear off. This lets you use the same pair of speakers in both a multichannel and two channel system in the same room, but still enjoying a much higher quality two channel experience than you might have using just a processor or receiver. Modern receivers and processors can do a very nice job with two channel audio as well, but as they are primarily geared towards a multichannel environment, using a separate, dedicated two channel integrated can give you both better two channel performance, and a high quality pair of amplifiers for your front speakers, without being overly complex. I fully tested this feature with the STI, and it made it much easier to integrate it into my existing system.