What Does It Take To Turn The PC Into A Hi-Fi Audio Platform?

JDS Labs O2+ODAC Combo

The O2+ODAC that JDS Labs (among others) manufactures, based on an open source design, is the most innovative concept in our round-up.

In 2011, a mysterious blogger who used the handle "NorthWest Audio/Video Guy" (NwAvGuy) began ranting about the snake oil he believed was being sold to the audiophile community. He set out on a personal crusade to design and build a low-cost headphone amplifier that, through blind tests, could not be distinguished from the Benchmark DAC1.

That design eventually became what's known as the "O2" (from Objective2) headphone amplifier. NwAvGuy went on to create an implementation of ESS' ES9023 chip to function as a DAC feeding the O2, using similarly objective criteria. That latter device came to be known as the "ODAC" (from ObjectiveDAC). Both devices can easily be connected and integrated into a single enclosure.

The O2+ODAC is an uncommon design by most standards. The headphone amplifier, in particular, was originally designed with battery-powered operation in mind (for portability). While the JDS Labs implementation does away with the batteries, it retains many of the portability-related design choices. It employs an external AC transformer, not the internal one you'd find on most comparable DAC/amps. There are no RCA stereo outputs at all. And the O2 does not use an amplifier chip (like the TPA6120A2), but rather a custom design on the output stage.

Feature-wise, the O2+ODAC is really barebones. It has a 3.5 mm line-in connection up front, a mini-USB port in the back, and a 3.5 mm headphone-out jack. That's it as far as I/O goes. Controls are limited to a gain switch and an analog (high-quality) volume control.

Based on NwAvGuy's open-source license (which, paraphrasing, states: anyone and everyone can manufacture one of these without paying me a dime, as long as they don't change the design), a variety of manufacturers are now selling O2+ODAC devices.

In 2012, after being banned from the headfi.org forum for, according to his version of the story, criticizing one of that forum's sponsor's products, NwAvGuy started building a desktop-oriented version of the O2+ODAC, called the Objective Desktop Amplifier. The twist is that NwAvGuy mysteriously disappeared without a trace in mid-2012 before completing the ODA's design. Nobody seems to know why he stopped blogging or what happened to him. So we're left with the O2+ODAC to test, and a lingering dream of what the ODA could have been.

The manifestation we're testing today is provided by JDS Labs. It is sold fully assembled for roughly $290, including the required AC transformer. If you're nimble enough with a soldering iron, you can pick up the O2 do-it-yourself kit for $69, add the ODAC board for $99, and buy the transformer for $11. That'd get you going for about $180, not including the enclosure.

Aside from the performance commentary you'll find through the following pages, I encountered one specific problem with the O2+ODAC. After receiving and unpacking it, I clicked into high-gain mode, plugged in my Sennheiser HD 800s (300 Ω impedance), turned up the volume, and noticed that the sound was terrible, affected by massive distortion. It turns out that the supplied transformer isn't powerful enough to drive high-impedance phones using the high gain setting. Unfortunately, JDS Labs doesn't stock higher-power transformers, so a replacement wasn't an option. The only solution was to use the low-gain setting at much higher volume. That did successfully solve the distortion issue. But JDS Labs should consider, in my opinion, stocking AC transformers that better-support the high gain setting. Going one step further, transformers should really be included with the assembled product.

So, did NwAvGuy end up winning his crusade? Can the O2+ODAC be distinguished from the 7x-more expensive and 5x-larger Benchmark DAC2? Read on...

Update: We received the following response from JDS Labs:
"AC adapters for O2 are packaged separately because JDS Labs ships worldwide. There's little incentive to bundle AC adapters since each customer requires a unique plug. Thus, the items are presented separately for customer's selection. Our shopping cart reminds customers to choose an appropriate model. As of late December, we now stock a higher-power model for U.S. customers who need additional current; this represents less than 2% of customers, though. All European, Australian, and British AC adapters stocked by JDS Labs are high-power models."

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  • SuckRaven
    Bravo ! Awesome, and a very thorough review. Even though as you mention, audio gear is not usually the forté/emphasis of the reviews here, it's refreshing to have someone at least try to cut through the (more often-than-not) overpriced arena of bullshit that is the field of "high-end" audio. I applaud the review, and the effort. Keep up the good work. More please.
  • PudgyChicken
    Just wondering, why not test a Creative X-Fi Titanium HD or something like that alongside the ASUS Xonar? It would be interesting to see some of the differences between different PCIe sound cards in this matchup. However I understand that what you were really going for was showing the difference between price point and form factor at the same time, so perhaps not testing two PCIe cards makes sense.
  • kitsunestarwind
    The biggest thing I have found for the PC is no matter how good your DAC is , if your speakers and AMP are crap, then it will never sound better.People spend big money on DAC's and forget that you need a high Quality amp with very very low THD (total harmonic distortions) and a very good set of Full Range speakers with high sensitivity if you want good sound, instead of crappy (albeit expensive) computer speakers especially sets with a sub.
  • shahrooz
    this article just won Tom's Hardware Readers Elite award
  • maestro0428
    Wonderful article! I love listening to music and do so mostly at my PCs. I try to set up systems where audio is important in component selection. Although we all love drooling over expensive equipment, many times it is not all that necessary for an amazing experience. I'd love to see more! Including smaller, studio speakers as I believe that speakers/headphones are the most important part of the equation. Keep up the great work!
  • blackmagnum
    Don't forget that for PCs: the hardware is as good as its software (drivers).
  • Someone Somewhere
    Agree totally with this. It always annoys me when people say they're spending over $100 on a sound card, especially when it turns out that they're using Optical out, and the whole thing is basically moot.I now have a nice source to link to.
  • 1zacster
    The thing is you can't just pick up two sets of good headphones, try them on different DACs/AMPs and expect to hear major differences, it takes longer than 5 minutes for your ears to adjust to newer headphones and for the differences to actually show. This is like taking food from Left Bank and then bringing in a bunch of hobos and asking them tel tell the differences between the foods.
  • dogman-x
    I use an optical cable from my PC to a home theatre receiver. With this setup, stereo CD audio content is sent as raw PCM to the receiver, not compressed into DD or DTS. These days you can buy a very good quality home theatre receiver for less than $200. Audio quality is outstanding.
  • Memnarchon
    I would love to see ALC1150 in these tests too, since its widely used at most Z87 mobos.
  • outlw6669
    Excellent in depth review Filippo! It is good to see a bit of Tom's roots shining through after all this time :)
  • loosescrews
    I would have liked to see some hard to drive planar magnetic headphones in the mix (maybe some of the Audeze LCD-X or LCD-XC headphones or HiFiMAN something) and also a cheaper DAC/Amp solution like Maybe the Schiit Audio Modi + Magni or Vali. Another nice addition would be the Creative Sound Blaster Z Series ZXR with its TI Burr-Brown DAC.
  • BrightCandle
    Can we get game surround sound audio tested as well? A lot of the reviews recently are focussing on sound quality differences in music but as you have determined there really isn't any difference there. But there is a clear difference I can hear in the comparative videos of battlefield with cmss, sbx pro, razor and realtek on youtube videos and the different surround sound effects really do seem to change positioning quality. This remains the only reason I think a sound card is worth it over realtek but it would be good to get to the bottom of whether its just EQ or its genuine quality differences related to the HRTF or something else.
  • bstaletic
    Great article. I also came to similar conclusions. I had bought High Resolution Technolies Musicstreamer II 2013 edition for ~$140and an Asus (I don't remember which one) for ~70$. I have technics SU-V8 amplifier and Wharfedale E50 speakers (cool stuff, look it up). Muscistreamer made bass a bit better (though not everyone could hear the difference) and now I say it was a waste of money. Asus on the other hand could make a difference if you set it up correctly, but you have to do it for every album so forget about shuffle. Only DAC I'm willing to hear is DACmagic for ~$400 and I doubt I'm going to be impressed.Conclusion: Buy any PC (the cheaper the better), and spend the rest of money you have on speakers and amplifier. Also make yourown cables.
  • ilovetea
    What's the purpose to invest into some special pc hardware, if major reciever brands have digital inputs and also usually unify inflows of audio through digital filters? This makes the reciever to serve as DAC both supporting and limiting the final quality.
  • Someone Somewhere
    1591957 said:
    What's the purpose to invest into some special pc hardware, if major reciever brands have digital inputs and also usually unify inflows of audio through digital filters? This makes the reciever to serve as DAC both supporting and limiting the final quality.

    What I have been saying for quite a while.
  • vmnej
    Electronics are negilable. The hard part ist turn ing the electrical signal into a mechanical signal (sound waves). That' why most of the money should go into the speakers and then maybe room acoustics. I highly recommend a pair of Nubert nuPro speakers.
  • gaymer1984
    I have a challenge to lay down for the writers of this article as an audiophile.Nothing you have particularly referred to can be contested; you do get more features with more expensive hardware, but price isn't necessarily an indicator of quality and it is high quality audio you are looking for, not necessarily the price point. That assumption doesn't work with sound cards as the first point in the signal path to the speakers.My challenge is this: compare your ALC 889 to an E-MU 1616m PCI-E. The quality of the DACs is higher on this £250 board than other PC sources I've heard myself, and you aren't spending £2,000 to get there. I challenge you to NOT find a difference. Don't change anything else in the signal path - keep the cable that feeds to your amp, and the speaker cables the same. Then listen to audio you know very well, and you know has been recorded well. This is harder to find with current music.You aren't looking for things to sound "better" or "louder", you are looking for greater detail. A better stereo "image" as it is called, where you can place instruments being reproduced by the speakers in a notional 3-D space. That is the mark of "good" audio.I ask you to accept this challenge because without following up this statement of $2 is as good as $2,000 you will potentially mislead budding enthusiasts down a misguided path.
  • martel80
    Why not include readings from the RightMark Audio Analyzer? They don't tell you anything about how it sounds but still...
  • Someone Somewhere
    Oh, great.

    Do you believe that the E-MU 1616m is significantly better than their $2k amp? If not, then they're still not going to find a difference.
  • dogman-x
    Electronics are negilable. The hard part ist turn ing the electrical signal into a mechanical signal (sound waves). That' why most of the money should go into the speakers and then maybe room acoustics. I highly recommend a pair of Nubert nuPro speakers.
    Good point. These days most all speakers used in professional recording studios are powered. You plug the speaker into the wall, and give it a low-level audio signal. The power amp is built into the speaker. This allows the manufacturer to perfectly match the amps to the speaker drivers. It also allows active crossovers (much more accurate), and many other things to improve audio quality.
  • hannibal
    It is good to hear that on board audio has come this far. I am still going to use stupendous amount of money to audio, but it is nice to see that the difference is not catastrophic!You did find biggest differences when trying to drive those high impedance speakers with cheaper options. So when someone above said that AMP is very important your statement proves that.I also liked that you used high quality headphones is this test. Senheisers are normally very analytic, so warmer "output" normally does not harm them. Personal preference is also in big role in here, as the writer really seems to like Asus sound card in this test.The headphones are really good devices to bring differences between sound sources while speakers may make it easier to find out how the space is presented from the source. But in this case the speakers have bigger role in this than the source.The biggest problem with cheaper options are normally worse dis torsion (so a little bit more hoarse sound) and really bad pre amp. And when talking about hifi, the "feel" of the equipment is also important, even not measurable factor ;-)I would really much like to see this kind of test when using mobile phones vs dedicate Flack players. Is there difference? Can you use high quality headphones, or do you have to balance with easier impedance?
  • ojas
    Neither lower-end solution can drive headphones and speakers concurrently, let alone automatically mute speakers when headphones are connected
    My lowly ALC888S has both these features, they are adjustable driver settings.

    I'm really looking forward to the speaker test, since speakers appear to have very low impedences, so DF would be very low.
  • panzerknacker
    Very interesting article, I have been doing similar testing myself lately.I like the methods you use for testing and there are many things that I did not think of myself yet.The biggest complaint againts your testing method that I have is the fact that you do not do direct comparison, thus switching between sources DURING playback. I do believe that swithing during playback is absolutely necesarry to notice small differences between devices. In order to accomplish this you would have to build 4 systems that are exactly the same in terms of hardware (paying close attention to revisions of components, and maybe even using testing equipment te verify similarity) with the same HDD image put onto all of them. Then you should sync playback on all devices (this is fairly easy to accomplish manually) and use a high-quality input-select switch which does not introduce difference between the various inputs channels (resistance, etc).