Small, simple, swappable, affordable. Oh yeah, musical too.

I’m not saying that my requirements were particularly stringent for a small, entry-level desktop digital-to-analog converter (DAC) and headphone amplifier setup to use for reviewing earphones, IEMs and headphones, but JDS Labs’ Objective Line amp and DAC ticked all of my boxes. So, on Black Friday (yeah, I like a bargain), I added two little black boxes—the OL DAC and Objective2 headphone amp—to my stable of audio gear. 

Since then, I’ve gotten quite a few questions about this acquisition. Questions like, “Why separates,” “Why JDS Labs,” and, “How does it sound.” 

Why Separates?

Easy. Separates are the way to go if you want or need the flexibility to swap amps and DACs. Running separates also makes upgrading easier. Say a new DAC design comes out in a year or two, but you love the way your amp drives your finicky Sennheiser HD650s. No problem, swap the DAC, keep the amp. Same for the flipside. You have a really transparent DAC—like the OL DAC—that has just what you need for your computer audiophile setup, but you switched to a power-hungry planar headphone. Well, keep the DAC and swap in a powerful amp. Simply put, separates give you flexibility to get the right system synergy. And, as The Spirited Uncle M savagely preaches, “Shit in, shit out; it’s all about synergy bro.” 

Why JDS Labs? 

Why not? First and foremost, I’m a hi-fi/head-fi fan. I read reviews and seek opinions just like the rest of you. When it comes to computer audiophilia, two brands seem to have cult-like followings—one is JDS Labs and the other has a name that sounds like shit. In full disclosure, I run Schiit Audio’s Yggdrasil DAC in my main headphone and two-channel systems (it’s amazing). But, having read quite a bit about JDS Labs and their infatuation with measurements, I decided to give their products a shot. To my surprise, I’ve been using the little OL/O2 stack far more than expected (maybe I’m just spending too much time at the computer). 

How’s it sound?

The OL DAC: I know a lot of people say a DAC is a DAC is a DAC, but I’m not one of them. A DAC’s chipset and its implementation, among other things, play a very real role in determining how it sounds. Well, the OL DAC doesn’t really sound like anything, and I don’t mean that in a bad way. Quite the contrary. The OL DAC is audibly transparent, which makes it a great reviewer’s tool. But what about for the rest of you? 

Satisfactorily small and straightforward, the OL DAC was, as JDS Labs’ Jude Hopper and John Seaber tell me, “an accidental child.”

As the company was experimenting with single-unit prototype DAC/amp combinations based on the open source amp design philosophy of acclaimed audio blogger NwAvGuy, it became apparent that the best bench tests came by way of standalone self-powered units. A standalone DAC design also allowed JDS Labs to better implement its USB and Optical inputs—a move aimed at appeasing customer demand for support for games consoles, CD/DVD players and other devices. And, so, the OL DAC was brought to market. 

But let’s be honest, it’s not an “exciting” product—it’s just an affordable DAC ($139) that does its DAC duties well. And that’s why people love it. The roughly 4”x3”x1” box provides nothing but the basics. On the backside there’s one plug-and-play USB Audio Class 1 input (16/44.1 thru 24/96), one Optical input (16/44.1 thru 24/192), one gold-plated RCA 2.0V output, and a jack for the 15VAC linear power supply. On the minimalist front there’s a power button, USB/Optical slider switch and single green LED. Inside you get the premium AKM AK4490EQ DAC chip—which also appears in high-end audio components from the likes of Astel&Kern, ESOTERIC, Marantz and others—that’s summed by an ultra-low noise and wide bandwidth Texas Instruments OPA2227 operational amplifier. Done. 

As I mentioned, one of the things I appreciate about the OL DAC is that it’s very transparent—there’s no coloration, or hints of overemphasis in any specific area of the dynamic range. Mating it to my O2, Eddie Current Balancing Act or HiFiMan EF-6 allows the traits of each to become readily apparent, not to mention what my head gear or speakers are doing. For tube audio fans, eliminating the influences of an audibly colored DAC allows for more immersive and effective tube rolling. Add in the fact that the OL DAC has an absolute noiseless, pitch-black background and nice detail retrieval, and that whole search for system synergy gets a little bit easier. 

The downside here, if you can call it that, is that transparent can be “boring”. It’s not what I would consider especially lush or organic (my preference); it’s just clean and clear and conveys a good sound stage. But the point is that you can marry this little low noise, low jitter, low distortion DAC to any amp you wish and end up with banging budget audiophile results (did I mention that the OL DAC is $139?). There are no surprises with the OL DAC, and that’s not a bad thing at all. 

The Objective2 Headphone Amplifier: Meant to be married to the OL DAC, the O2 headphone amp matches it in shape, size and simplicity. What’s neat about the O2 is that JDS Labs allows for some simple customizations—you can choose the headphone jack size (3.5mm or ¼”), input type (RCA or 3.5mm), gain levels, and power jack location (front or rear panel), and whether to have it with or without a built-in DAC and rechargeable batteries for portable use. I went with a rear-mounted power jack and RCA input, so my front panel is nice and simple with just the power button, headphone jack, volume knob, gain button and a red LED power indicator (why red instead of green to match the OL DAC? I don’t know, but it kind of bothers my OCD).

So how’s the little black box sound? Well, it follows the open source amplifier design from the aforementioned NwAvGuy. In other words, it targets benchmark performance at a budget cost ($129). So, much like the OL DAC, the O2 amp aims for transparency. Or maybe a better way to put it is simplicity. 

For those of you that are used to colored amps, there’s nothing romantic about the O2. In fact, it’s likely to come off as a bit dry, a bit sterile, a bit, well, boring, just like the OL DAC. That is, unless your DAC is colored in another way. After all, all the O2 really does is amplify the signal in front of it, which means a great recording, a nice DAC and a stellar sounding headphone or IEM is what’s needed to put you on the path to #AudioNirvana.

The best thing about the O2, sonically speaking, is its versatility. It has the power and dynamic range to drive anything from a sensitive IEM to a power hungry dynamic headphone with authority. The semi-picky Sennheiser HD650, for example, gets plenty loud and hits with modest authority in high-gain mode. The O2 can also play any genre of music well, because, well, you’re hearing the music and the rest of your equipment for what it is. The caveat here is that you need to plan for this. Meaning, the O2 is going to do absolutely nothing to hide poor recordings, and if you favor a darker, warmer sound signature, you’ll want to choose a headphone with those characteristics rather than something analytical like the reference level AKG K701. Or, you could always dabble with some EQ software to fine tune your setup. 

With the OL/O2 combo, which is what I assume a lot of you reading this review are considering purchasing, you’re getting a pair of neutral performers, nothing more, nothing less. This stack isn’t going to romanticize your music collection. Rather, it’s going to allow you to focus on the music and hone your efforts on choosing the IEM or headphone that best suits your musical taste.

I’ve mainly been running the rounds with the Audioquest Nighthawk, Beyerdynamic Amiron Home, Meze Audio 99 Classics and Sennheiser HD650. The OL/O2 drives each of these headphones with ease and enjoyment, although none come off as being quite as airy, lush or three-dimensional as when pushed with a powerful tube amp (just my personal preference), the warm characteristics of each is conveyed cleanly and with good dynamics. Although these are all darker sounding headphones, I liked the pairings because it brought some balance to the neutrality of the OL/O2 stack. The consistent instrument separation and detail retrieval of the OL/O2 pairing is solid. The sound stage is modest, extending maybe three to four inches out around the head. Stereo imaging is dead center, although I do selfishly lust for a more holographic presentation. As someone who favors really lush sounding gear, this little stack can sound a bit flat to my ears—bass notes hit with impact, but often lack resonance; mids are clear, but are light on warmth; treble is crisp and detailed, and never too brittle, but airiness and texture seem overly controlled. But all of this is inherent in neutral, transparent solid state amps and DACs. Boring can also be better; the neutrality of this combo makes it an excellent setup for audio purists and gear reviewers because it reveals more accurately what a particular recording, headphone or IEM can and cannot do. 

Overall, I generalize the OL/O2 stack as being crisp, clear, controlled and consistent. Sure, it can be boring for those that favor the ooey gooey goodness of lush and distorted tube gear, but boring isn’t always bad. In fact, these little black boxes are probably one of the best places to start for new budget-minded audiophiles looking to learn just what it is they like and lust for.