The DACport's technical capabilities and sound quality were as notable as its form factor back in 2009, kicking off the current generation of highly portable, high-quality, high-resolution USB models. One of the DACport's features is still unmatched by its newer competitors: Its headphone amplifier is based around a Class A design, which proponents argue produces better audio quality than Class B and D designs. This approach also means that the DACport is less energy-efficient, as power not used to drive headphones is converted to heat — the DACport gets warmer than the other units here, though never outright hot. However, while other models in this roundup use asynchronous data transfer, the DACport uses adaptive transfer — in which the computer controls data transfer, potentially increasing jitter — but in combination with the company's proprietary jitter-reduction technology.
Following the DACport by a few years, AudioQuest's $149 DragonFly takes the DACport's basic topography — USB input on one end, and a 3.5mm headphone jack on the other — and further shrinks and simplifies it. A standard USB plug is integrated into the unit, allowing the DragonFly to plug directly into a computer like a thumb drive. (Indeed, the device looks essentially like a thumb drive.) The DragonFly also eschews a physical volume control, relying instead on the host computer's software volume setting. A recent hardware revision, to version 1.2, included some improvements to the device's audio circuitry.
The DragonFly, designed in cooperation with DAC expert Gordon Rankin of Wavelength Audio, is charmingly small, well-built, and offers impressive performance. Despite its small size, the unit feels substantial, and it has a pleasant-to-touch rubbery exterior. The DragonFly logo on the outside lights up to indicate (by the color of the light) the current sample rate (up to 96 kHz/24-bit). AudioQuest includes a leather carrying pouch and a cap for the USB connector.
Due to its thumb-drive-like design, heavier headphone or interconnect cables can cause the DragonFly to strain your computer's USB port, so the company also sells the $17 DragonTail: a short USB extension, based on the company's Carbon line of high-end USB cables, that also prevents the DragonFly from blocking tightly-spaced ports on your computer.
The DragonFly's small size and all-in-one design make it a particularly good match for use with a laptop on the go. Thanks to this convenience, I frequently grabbed the DragonFly for portable listening.
Meridian is a big name in the world of digital audio, and in 2013, the company jumped into the portable DAC/amp market with the $299 Explorer. The Explorer is an ovular, aluminum tube, closer in size to the DACport than the DragonFly, but much lighter; a flat, rubberized underside helps the device stay in place. Like the DACport, one end of the Explorer features a Mini-USB input, while the other hosts a software-volume-controlled, 3.5mm headphone jack. The output end also features an auto-switching 3.5mm analog/digital output, much like the one on most of Apple's recent computers. You can use the analog output to connect to a full-size stereo or powered speaker system; the optical output lets you use the Explorer as a high-quality USB-to-optical converter, so you can connect your computer to a higher-end DAC that lacks USB input.
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