Ever since AudioQuest released its miniscule DragonFly combination DAC and headphone amplifier, I’ve been fascinated by miniature combo components. Ideal for headphone listeners who want to use their computers as a source for music playback, combination DAC/headphone amplifiers provide superior sound (way superior) to the typically wimpy headphone amplifiers in home computers. In addition to driving headphones, combination DAC/headphone amplifiers can also drive line-level inputs on an amplifier if you use an appropriate cable. But before proceeding with this review, we need a catchy term for this genre of equipment; calling them combination DAC/headphone amplifiers doesn’t exactly roll off the tongue (or the keyboard). I rather like a term I’ve seen various places on the Internet: dongle-DAC. That reflects the fact that most of the combination DAC/headphone amplifiers attach to a computer’s USB port via a short USB cable. Some of them can plug directly into the USB connector, but that can put a lot of strain on the connector, especially if your headphone cable is stiff. So dongle-DAC it is, at least in this review. Incidentally, AudioQuest started the dongle concept when it released a dongle cable it called the DragonTail to use with its DragonFly. Since then, most dongle-DAC manufacturers include a dongle cable with their DACs.
Light Harmonic began life as a manufacturer of very-high-end DACs. Its Da Vinci was stunning in sound quality and styling, and equally stunning in price: $20,000. When DSD recordings became available, Light Harmonic’s Da Vinci Dual DAC was one of the first that would play that format. Instead of producing a DAC that would do both PCM and DSD, it built a double-layer DAC that stacked a DSD-only and a PCM-only DAC. Pricing was commensurate with this uncompromising approach: $31,000. And if that seems high, Light Harmonic has announced a model called the Sire with a projected price of $120,000.
When Light Harmonic wanted to enter the dongle-DAC competition, it created a division called LH Labs, and used a crowd-funding approach to fund the design. To generate excitement, LH Labs needed something to appeal to the younger crowd targeted for the funding campaign, so they called the device the Geek Out. Apparently the name was a stroke of genius. Since the amounts raised wildly exceeded the target, LH Labs decided to offer three versions of the Geek Out, with amplifiers of different output power. The $199 USD Geek Out 450 reviewed here has an output capability of 450mW, while the $299 Geek Out 1000 produces a full 1000mW (that’s a full watt, enormous for headphones). There’s also a $289 Geek Out IEM 100, which produces 100mW and is optimized for very sensitive in-ear monitors that could be shredded by overly powerful amplifiers. All versions of Geek Out ship with a dongle cable called a Slacker and a cloth carrying case. The Slacker, which is just a USB extension cable, is only 6" long, and if used with a desktop computer (at least with mine), leaves the Geek Out hanging in the air. However, you can order a second Slacker (for $19) and daisy-chain the two together.
Geek Outs don’t have a separate power supply; they’re powered by the computer’s USB connection, which is also their only audio input. They do have two output connections: one with a very low output impedance (.47 ohms) and the other with a 100-times-higher (but still low) 47-ohm impedance. The former output should drive any headphone, including the lowest-impedance models, while the latter output should drive line-level inputs and high-impedance headphones. Both outputs can be used simultaneously.
Measuring 3" by a smidgen over 1¼", the Geek Out is larger than the original DragonFly, but smaller than other dongle-DACs I’ve seen. Connectivity is via a USB Type A connector on the input end and two each stereo output jacks on the output end. Headphones plug directly into one of the Geek Out’s output jacks; if your headphones have a ¼" plug, you’ll need an adaptor, but your headphones probably came with one. To connect a Geek Out to an amplifier, you’ll need an interconnect cable with a stereo plug on one end, splitting into two separate cables terminated by RCA plugs. Fortunately, given the popularity of headphones and associated electronics, such cables are now common. My Geek Out 450 has a silver case, while the Geek Out 100’s case is black, and the Geek Out 1000’s red.
The first time you touch a Geek Out that’s been running awhile, you could probably guess from its hot case that the Geek Out’s headphone amplifier runs in Class A. The user guide warns that the Geek Out can reach temperatures of 158° Fahrenheit. Ouch!
Sometimes a dongle-DAC leaves out a few features you’d find on a full-size DAC, but not the Geek Out; it uses an ESS 9018K2M chip to play PCM sample rates of 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz, 352.8kHz and 384kHz in 16-, 24-, and 32-bit depths, as well as DSD64 and DSD128. That’s virtually everything commercially available, although there are a few DSD256 recordings have been released. Lights on the bottom of the Geek Out indicate the sampling frequency and type of input signal.
The Geek Out has two filters—Time Coherence Mode and Frequency Response Mode—that you can select by pressing one of the two buttons on the side of the unit. LH Labs describes the filters as follows: “Time Coherence Mode (TCM) uses LH Labs’ minimum-phase digital filter and time optimization algorithm, which removes all post-ring from the original signal and realigns the impulse response. This presents the listener with a more well-defined and natural soundstage. Frequency Response Mode (FRM) uses a slow roll-off linear-phase digital filter with our proprietary frequency-domain optimization algorithm. This mode gives you a smoother and clearer sound with even lower THD+N than our previous version.”
Like most DACs, the Geek Out works with Linux and the Macintosh operating systems without a driver, but the Windows operating system requires a driver. LH Labs updates the Geek Out driver and operating system, so you should visit its website occasionally to see if there are new versions available.
Setting Up and Using the Geek Out
For this review, I used my desktop computer, an aging Dell Inspiron 530, running J. River Media Center version 20 as the server software. I plugged in the Slacker USB cable provided with the Geek Out into my computer and to the Geek Out, and plugged my headphones into the .47-ohm output jack. I tried several headphones in my collection: HiFiMAN HE-400, AKG K701, AKG K712, and Audeze LCD-X. Only the K701s needed more power than the Geek Out could provide. I was surprised that the low-sensitivity HE-400s worked with the Geek Out. But they not only worked; they sounded better than they have with most other headphone amplifiers I’ve used. Go figure. The Geek Out had no trouble at all with the very sensitive LCD-Xs, and since they are the best headphones in my collection, they are the ones I used for listening impressions. It may seem goofy to use $1699 headphones with a $199 dongle-DAC, but the Geek Out was not embarrassed by the pairing.
Since I used a Windows computer as my server, I had to download and install the Windows driver. That process was simple and straightforward. There’s a detailed on-line instruction sheet that tells you how to download the driver and install it into Windows; however, there’s nothing telling you how to install it into your server program. Since LH offers four drivers—an ASIO driver, a WASAPI driver, a Kernel Streaming driver, and a Direct Sound driver—some suggestions about which is recommended for popular server programs like J. River Music Center and Foobar2000 would have been helpful; this stuff is not intuitive. Drawing on past experience, I used the WASAPI driver with J. River Media Center.