To say the USB market is saturated would be an understatement. To say the affordable USB DAC market is crowded, would be even more so. I define “affordable” as under $1000. There are a slew of new products under $300 that have flooded the market, but those are mostly, if not all, considered “portable” devices. Affordable USB DACs come in every conceivable size and shape, with varying resolution capabilities, power schemes, and build quality. Most offer a single USB input, since a computer is the assumed source, but others offer additional S/PDIF inputs as well.
USB DACs have taken high-end audio by storm due the popularity of using computers as digital source components. The optical disc player is going the way of the dinosaur according to those who claim to be ahead of the curve. This may be partly due to the fact that USB DACs can be made these days with a small footprint, and are easy to integrate into a system.
Affordable USB DACs are most often hub powered. This means they get juice from your computer via the same USB cable the data is sent through. Some also are supplied with external wal wart power supplies, and some are even upgradable with aftermarket linear power units. In general, affordable USB DACs are also no frills, focusing on sound quality. This means you rarely see a sample rate indicator, or even a power off switch. This purist approach keeps costs down and keeps the focus on sonics.
We have the Ciunas, the latest DAC from John Kenny, in for review. As DAC designer based in Ireland, Kenny has been making USB to S/PDIF converters and USB DACs for a number of years now. And if you'd like to know more about him and his products, check out the interview at the conclusion of this review.
The Ciunas is housed in a small but sturdy chassis, and the build quality is very nice indeed. There is an on/off switch on the front, a USB input, and a pair of RCA outputs. The DAC is 192 Khz, 24 bit capable, and is compatible with Mac and Windows, the latter requiring a driver which you can download. The chassis can be finished in black or silver. The DAC is priced 550 Euros, plus shipping; the US price will be around $750 depending on conversion rate.
According to Kenny, "the Ciunas feeds an I2S signal to a PCM5102 BB/TI DAC chip. The PCM5102 DAC sounds superior to the ESS Sabre DAC ES9023 used in one of my previous DAC products. Each element, significant to achieving the best possible signal quality, has been addressed. Battery power provides extremely low PS noise - one of the most important factors in digital audio. The high current output battery used (120 Amps instantaneous current) is the most stable power supply available for digital circuitry. Using this isolated power supply avoids issues of common mode noise & ground loop noise, often associated with non-isolated power supplies. Whereas other USB devices use 'add ons' such as isolators, special power supplies (often battery PS), ground lift techniques, etc., there is no need or advantage to such devices with the Ciúnas range - these issues are already dealt with & designed in from the ground up. The self-powered Ciúnas mitigates the influence of the PC's noisy power supply. As the 5V USB feed is not used or connected in any of the Ciúnas devices there is no influence from this supply; this means special USB cables, which separate out the 5V Vbus, wire are not needed - a wider range of options are available when choosing a USB cable which are not limited by this consideration."
Above, Kenny describes the power scheme used in the Ciunas, which may be its secret weapon. Specifically, it is battery powered, so it does not have any of the noise issues associated with hub power. However, there is a special twist. The battery is drip charged with either a supplied USB charger cable, plugged into a separate USB port on your computer, OR via an external power supply that can be rated between 5V and 12V, which you can purchase for a few dollars.