QR Code contains TinyURL of this article.Objective2 Headphone Amplifier and ODAC

Objective2 headphone amplifier with integrated DAC, Audio-Technica ATH-M50X headphones and Apple MacBook

I’ve always enjoyed music. I will sit for hours with my headphones on, my eyes closed and iTunes belting out some rock. When I’m listening, I’m involved in the experience, my feet will tap almost without conscious control, I’ll drum on the furniture, perhaps even bedazzle an imaginary audience with my extraordinary skill on the air-guitar.

Since my early teens, when scratched or dirty records upset my listening enjoyment with their hisses, pops and crackles, I yearned for only the best audio quality. Then, with the introduction of the compact disc, digital audio brought the promise of noise-free music. I bought my first CD player when the only disc available was Dire StraitsBrothers in Arms — which I played endlessly. Over the years that followed, I collected CD‍s by the hundreds. I had a great music collection but it lacked somewhat in portability. When Napster launched I was there, greedily downloading everything I could get my hands on. Then came the iPod. I bought one of the first models, and immediately filled it to capacity. Finally I had both a decent library and portability. I travelled Europe with my iPod clipped to my belt, those iconic white earbuds marking me as an early adopter.

I was an aspiring audiophile. I read all the periodicals, soaked up the details of every review and dreamed of the days when I, as a multi-millionaire, would surround myself with kit from Linn, Nakamichi, McIntosh, NAD, Denon… and I would have the best listening experience any man could ever imagine.

Yet despite my enthusiasm, I was cynical of the claims made by some of the audio equipment manufacturers and particularly those of the purveyors of audiofool accessories. Could a £2,000 cable really result in a better sound than a £20 one? Do gold-plated connectors make a difference — on a digital interconnect? Magic crystals? Cable risers? Felt pads? The list goes on.1

Sometime around the year 2011 (I think) I read an article on the Web about an audio engineer who’d challenged some of the outrageous claims made by the industry. This engineer, known only by his handle NwAvGuy, posited that spending tens of thousands of pounds on audio equipment wasn’t really necessary. Of course, this blasphemy was vigorously denied by those with a stake in the game. So NwAvGuy did something extraordinary. He (I’m assuming a man) designed and built a headphone amplifier with amazing audio fidelity — from around £50’s worth of components — and he open-sourced his design, making it available to all. Then he challenged anyone to compare any other equipment against his in a blind listening test, so that they might prove their claims of superiority. Talk about having faith in your product.

NwAvGuy went on to design — and again open-source — a DAC that could either by paired with, or integrated into his amplifier. He called the now legendary amplifier the Objective2 (or O2). The DAC became known as the Objective DAC (or ODAC). Then, for a grand finale, NwAvGuy simply vanished, adding a certain mystique to the Objective2 story.

The Objective 2 headphone amplifier with integrated DAC

The O2 intrigued me. I wanted to try it. Now my days of messing around with a soldering iron are long behind me, so I was happy to find the desktop version of the Objective22 — complete with integrated ODAC — for sale from the Swiss outfit, Head ‘n’ HiFi.3  I placed my order and, earlier this week, took delivery of this almost fabled bit of hardware.


The amp connects to a digital source via USB. It also boasts a two-channel analogue input. For myself, I have it connected to my MacBook over USB, so I’m taking full advantage of the ODAC. The only other rearward connection is the AC power input.

Rear of the Objective 2 headphone amplifier with integrated DAC

Once I have connected the O2 to the MacBook, the ODAC appears as an option in the Output tab of the Sound preferences pane. There are no drivers to install. I select the ODAC and we’re good to go.

OS X audio output preference pane showing the ODAC option

I plug my pair of highly rated Audio-Technica ATH-M50X headphones into the O2 and select The Division Bell, my favourite Pink Floyd album, in iTunes. I click the play icon…

So how does it sound? Here’s where I should wax lyrical about audio fidelity, sound-stage, presence, bass, treble, mid-range… I should enthuse about depth, warmth and clarity. I should write emotional sentences describing how I’m hearing things in my music that I never noticed before.

But here’s the thing, an amplifier’s sole purpose is in it’s name. It should only amplify the sound. It should not colour it in any way. It should not add warmth, whatever that means. It should not ramp up the bass. It should certainly not hiss or crackle. A good amplifier should provide the listener exactly that sound that the producer, engineer and artist signed-off on in the studio. Only then will the listener hear the music in its purest form.

That’s what NwAvGuy designed the O2 to do and it really delivers.

This is an amplifier that can drive just about any headphone out there, even the power-hungry ones, and it does so without changing the sound. I turn the volume dial up half way, on 2½× gain, and it’s louder than I can bear. Yet there is no hint of noise or distortion, nothing to get in the way of the music. It sounds fantastic.

In one of NwAvGuy’s blog posts, I had read that the O2 is silent in operation. That the amplifier itself puts out no noise. I pause The Division Bell and turn the volume control all the way up to eleven, total unadulterated silence. Wow. The bargain-basement O2 amplifier is truly a giant.


I like the Objective2. For me, it lives up to the hype, the promise… the legend. Not only do I find myself listening to music with a smile on my face, but I’m also thrilled to finally own this little piece of Internet history and folklore. I only wish I’d bought one sooner.

Objective2 headphone amplifier with integrated DAC, beside an Apple MacBook
  1. I have deliberately not linked to any of the suppliers of the audiofool products I’ve mentioned as they really don’t deserve your attention. ↩︎

  2. The original O2 was a battery-powered fully portable unit. NwAvGuy also designed a desktop version, sans batteries, with further refinements to the original. ↩︎

  3. I can’t praise Head ‘n’ HiFi enough. The customer service provided by Stefan is second-to-none. He hand-builds the amps and ships them, well packaged, within days of receiving an order. He’s communicative and even refunded some money to my account when he found a better shipping option for me than the one I had chosen from his website. Now that’s how you do business. My hat is off to you Stefan. ↩︎