JDS Labs O2+ODAC Combo Review – Objective2 Headphone Amp with ObjectiveDAC


DAC or Digital Audio Converter is basically what connects your digital audio source to your analog speakers, and Amplifiers are basically what makes the volume of the audio louder. Aside from converting the signal and amplifying it, a good DAC/AMP can also make the audio quality better. While a bad DAC/AMP can ruin the audio quality, may cause some distortions or even unwanted noise. Usually a DAC and an AMP are two separate components. But there are also components that both have a DAC and AMP. Today we are going to look at the JDS Labs O2+ODAC Combo or the Objective2 + ObjectiveDAC (Headphone Amplifier and DAC) based on the original designs of a mysterious Electrical Engineer/Blogger called NwAvGuy. There are lots of DAC and AMP out there, and they usually come with a high price tag, specially the good or elite ones. And sometimes prices could reach up to $2000 (or probably higher) just for a DAC. Now NwAvGuy, through his ODAC and O2, showed to us that you don’t need to spend thousands of dollars to get a great performing DAC and/or AMP. Is that right? Find out in my JDS Labs Objective2 and ObjectiveDAC Combo review below.

JDS Labs Objective2+ObjectiveDAC Combo Review

JDS Labs O2+ODAC Combo Review

The Objective2 headphone amplifier and ObjectiveDAC are actually quite controversial pieces of audio components. Like I said earlier, JDS Labs’ O2+ODAC is based on the open source design of NwAvGuy (short for Northwest Audio Video Guy). NwAvGuy said in his blog that he can build a way cheaper DAC and Amplifier that can match the sound quality of the Benchmark DAC1 in blind listening test. He also said that the “the O2 amplifier was created as a simple, low cost, minimalist design delivering 100% transparent performance into nearly any headphone. The ODAC takes the same minimalist approach to transparency.”

On top of that, he also emphasized that he is not selling anything and does not profit from it. In fact he licensed his DAC and AMP under the Creative Commons License. “Anyone is free to use the O2 design, as presented here, if they comply with the Creative Commons License. I don’t want any revenue from the O2 but I do humbly request everyone please respect the license which includes proper attribution.”

Basically, Objective2 and ObjectiveDAC are two separate components, and the JDS Labs O2+ODAC is a 2-in-1 unit. It’s assembled in accordance with NwAvGuy’s default, high-performance specifications. It features very low THD and noise performance, has extremely low output impedance, able to drive most (if not all) dynamic headphones, features insignificant jitter of around -106dB, supports 24-Bit audio and has a natural frequency response that is within +/- 0.1dB.

JDS Labs’ O2+ODAC Combo are enclosed in a hard aluminum shell and comes in either Black Edition or Silver Edition. You can also customize whether the power jack is located in front or rear mounted; headphone jack is 3.5mm or 6.55mm; the 3.5mm DAC line-output can be placed in front or in the rear or use a rear RCA line-output instead; and you can also choose the gain amount, whether 1.0x, 2.5x / 1x,3.5x or 2.5x,6.5x.

Let’s take a closer look on the O2+ODAC Combo below and discuss more of its features and specifications.

JDS Labs O2+ODAC Combo Specifications

Frequency Response+/- 0.1 dB (10 hz – 19 Khz 24/44)
THD+N 100 hz 0 dBFS0.00%
THD+N 20 hz –1 dBFS0.00%
THD+N 10 Khz –1 dBFS0.00%
IMD CCIF 19/20 Khz –3 dBFS0.00%
IMD SMPTE –1 dBFS0.00%
Noise A-Weighted dBu 24/44-102.8 dBu
Dynamic Range> 110 dB A-Weighted
Linearity Error -90 dBFS 24/440.0 dB
Crosstalk 0 dBFS Line Out 100K-93.5 dB
USB Jitter 11025 hz J-test 24/44Excellent
Maximum Output Line Out 100K2.0 VRMS
Distortion< 0.005%
Objective2 Headphone Amp
Frequency Response+/-0.1 dB (20Hz-20kHz)
THD 1 Khz 150 Ohms0.00%
IMD CCIF 15 Ohms0.00%
Noise (ref 400 mV)-105 dB
Max Output (33 Ohms)613 mW
Max Output (150 Ohms)355 mW
Max Output (600 Ohms)88 mW
Output Impedance0.54 ohms
Crosstalk (15 ohms)-65 dB
Channel Balance (50% volume)0.6 dB
Gain2.5x and 6.5x*
Volume Potentiometer TaperAlps 15A or 3B
Analog Output3.5mm or 6.35mm*
Analog Input3.5mm
Digital InputMini-USB
DAC Line Output3.5mm or RCA**
Power Input14-20VAC
Data Support
Audio Formats16/44, 16/48, 16/96, 24/44, 24/48, 24/96
InterfaceUSB, Audio Class 1
Native Driver OS SupportWindows XP & Later, OS X x86, Linux
Case Dimensions (mm)108.50 x 80.00 x 29.50
Case Dimensions (in)4.27 x 3.15 x 1.16

A Closer Look on the Objective2+ObjectiveDAC

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The O2+ODAC Combo comes in a very simple packaging. There’s the JDS Labs logo in front of the box and a “Made in USA” logo at the back.

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Inside the box you get the O2+ODAC Combo and a microUSB to USB cable. The O2+ODAC does not have an internal battery and the package didn’t came with an adapter. You will have to purchase an AC-to-AC adapter separately. Of course you can buy a compatible and recommended adapter from JDS Labs.

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The O2+ODAC Combo features a hard aluminum shell that houses the components. It might be confusing, but the JDS Labs Objective2 (the one without a built-in ODAC) also looks like the O2+ODAC combo. By the way, if you switch off the amplifier, the line-in becomes the line-out for the ODAC. No power is required for you to use the DAC feature. Of course when you switch it off the volume knob doesn’t work as well.

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The O2+ODAC Combo is only 108.50mm x 80.00mm x 29.50mm and it is in accordance with NwAvGuy original design. You might see the same product from another manufacturer since this is basically an open source design under the Creative Commons Attribution-NoDerivs 3.0 Unported License.

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At the back you will see the miniUSB source input plug and the 14v power jack. The power jack can be placed in front or at the back of the O2+ODAC.

JDS Labs O2+ODAC Combo Review-13

Above is a photo of an empty shell of the Objective2/OjectiveDAC. Notice the lines inside the casing? That’s where the PCB slides in. By the way, that’s a pretty hard shell and won’t bend easily.

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Above is the front and rear view of what’s inside the thick aluminum shell. There are two layers of PCB, one for the Objective2 amplifier and the other one is for the ObjectiveDAC. The smaller square PCB located on the lower left corner (which is on top of the larger PCB) is the DAC portion of this component. While the larger bottom portion PCB is the Objective2 amplifier. You’ll also notice that there is an attribution printed underneath the PCB of the Objective2.

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There are two major components soldered in the ObjectivedDAC: the Tenor TE7022L and ESS ES9023P.

The TE7022L is a low power, cost-effective, USB 2.0 Full-Speed compliant Audio Streaming Controller. It features one independent stereo playback and recording pairs and one IEC60958 S/PDIF receive and transmit streaming pair with independent volume control, supporting 16/24-bit resolution and up to 96K Hz sampling rate.

The ES9023, on the other hand, is a 24-bit stereo audio DAC with an integrated 2Vrms op-amp driver. Powered by the industry proven Sabre DAC technology, the ES9023 combines best-sounding audio with lowest system cost and highest performance into the ideal D/A converter for line-level output applications such as Blu-ray players, CD/DVD players, set-top boxes, digital TVs and audio receivers.

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NwAvGuy’s original Objective2 has a built-in rechargeable battery, however the O2+ODAC Combo doesn’t have an internal battery since the space which the batteries are supposed to be placed are replaced by the ODAC. Unlike the ODAC, the Objective2 has more components soldered into the PCB. One major component used in the Objective2 is the JRC 4456AD. It’s basically an integrated circuit with high-gain, high output current dual operational amplifier capable of driving ±70mA into 150Ω loads (±10.5V output voltage), and operating low supply voltage (V+/V-=±2V~). The 4556A combines many of the features of the popular NJM4558 as well as having the capability of driving 150Ω loads. In addition, the wide band-width, low noise, high slew rate and low distortion of the NJM4556A make it ideal for many audio, telecommunications and instrumentation applications.

Now let’s put JDS Lab’s O2+ODAC Combo to the test.

Testing and Sound Quality

In testing the JDS Labs Objective2+ODAC Combo I used the German Maestro GMP 8.35 D Monitor and B&W P7 headphones, and my old Altec Lansing VS2421 desktop speaker. The two headphones have low impedance, are easy to drive and doesn’t really need additional amplification. They are both well balanced and are very transparent. Unwanted noise, humming, hissing or any distortion could easily be distinguished or heard. Meanwhile there’s nothing really special about the VS2124. It a decent and affordable desktop stereo speaker with a subwoofer, but this is the one the benefited the Objective2’s amplification.

I have two sources while testing the O2+ODAC, one is from my desktop PC with an Asus Maximus VI Impact motherboard and the other one is from my laptop. The motherboard features a SupremeFX Audio core with TI LM4562 HiFi audio OP AMP, while the laptop doesn’t really have anything special.

Installing or connecting the O2+ODAC is very easy. Simply plug it to the power source using the recommended AC-to-AC adapter, and connect it to the audio source using the USB cable. No additional driver is required, and the computer easily detects and switches to the O2+ODAC. For best results, be sure to set the sample rate and bit depth of your computer to the highest setting, usually 24bit and 96000 Hz (studio quality).

Speaker Options

Be sure to turn the volume of your PC to maximum, and before actually listening via the O2+ODAC, be sure that the volume knob in the O2 is set to 1. You definitely do not want to damage your ears specially if you are using a headphone or IEM/CIEM! From there, slowly turn the knob up to the desired volume.

Sound so Clean and Crystal Clear!

First wave of test was using the headphones. I was amazed how clean and clear the sound was. I mean, listening directly to the computer’s lineout was good already, but via the O2+ODAC was definitely even better. I was also surprised that there were some sound elements that I was able to hear now, that I haven’t really noticed before.

Now listening to nothing was impressive. I sometimes hear some very very tiny sound, feedback or hiss when directly connected to the source. Even if I turn the volume of the Objective2 to its maximum, I could not hear any hiss, static sound, or any noise at all. It was as if my headphones were not connected to the O2+ODAC at the first place.

While listening to lossless format tracks (FLAC) the sound quality was simply great. I did not notice any distortion in the sound or any coloration at all. The amplifier simple amplifies the audio signal and did not alter the audio quality at all. However do note that the O2+ODAC is not some magical component that will make a poorly encoded MP3 file sound any better. If your source is bad or has a poor sound quality, expect that you will also get the same poor audio quality.

There’s no problem in using the ODAC feature alone since you don’t need any power or turn the volume knob. However when using the Objective2, I noticed that the left and right signal was unbalanced when the volume knob is set almost to its lowest point. But the audio becomes balanced again as you turn the volume knob a little bit higher. But seriously this is just a very minor thing because nobody would set the volume knob almost to its lowest point when you are actually using it.

My Desktop Speaker is Alive Again!

After listening to some music using the B&W P7 and GMP 8.35 D, I then connected my old Altec Lansing speaker to the O2+ODAC.  I have been using this speaker for many years now and I really thought that it was time to change it since it wasn’t performing very well, even when I adjusted its bass and treble settings. I was pretty surprised that my speakers noticeably produced a better sound quality than before. Aha, so it turns out that the on board SupremeFX audio core wasn’t really performing well. If it did, the O2+ODAC Combo was simply even better than my motherboard’s built-in sound card.

I also noticed that not only my experience with listening to my favorite tracks became better, but watching movies also became more immersive and fun as well. Sound was louder and clearer, and I don’t have to change any settings in the ffdshow audio decoder configurations anymore just to increase the volume, like what I do before the O2+ODAC came.

I haven’t actually taken advantage of its Gain feature since the current headphone collection that I got is easy to drive and doesn’t necessarily need amplification. However I did tried using gain but I have to turn down the volume knob down since the sound got too loud already. Before getting one, be sure that the gain settings is in accordance with what audio gear you have. You can easily customize this from JDS Labs’ site before they ship it out to you.

Price and Availability

The JDS Labs O2+ODAC Combo is available starting at $279 from JDS Lab’s online store. Like I said earlier, you can customize how the O2+ODAC will look and how high or low the gain can be. You also need an AC-to-AC adapter with a minimum 14VAC output, since this device is not battery operated.

JDS Labs O2+ODAC Combo Review: Conclusion

After using the JDS Labs Objective2+ODAC Combo for several weeks, I am very well impressed with its performance given the price point. Aesthetically speaking, it looks simple and clean, not to mention the paint job is great as well. It may not be as fancy as compared to other DAC/AMP but it’s definitely very sturdy thanks to its thick aluminum shell.

Performance wise, the sound quality of the O2+ODAC is great and I bet it could rival other DACs/AMPs out there that are probably priced twice or 3x than this one. The audio quality is very clean and doesn’t alter or distort the sound signature even when using the amplifier. It can drive most of the headphones and IEMs, even speakers easily. Probably if there is one thing I wish could have been included in the combo package is an internal rechargeable battery, so that I can use it on the go. Of course that would mean making the enclosure a bit lager to house everything.

Do you need the O2+ODAC Combo for your Desktop PC? It depends on your current setup really. If you already have a high end sound card that produces a good amount of audio quality and amplification, then investing on the O2+ODAC might not be really a good choice, unless money is no object to you. However, if your PC or laptop doesn’t produce a good sound quality, or probably you hear some weird noise coming out from your system, and it doesn’t have amplification (and you need one), the JDS Labs’ O2+ODAC Combo is definitely a great upgrade to turn your PC into a HiFi audio system.

The JDS Labs Objective2+ObjectiveDAC Combo is a great small piece of component that definitely performs great for its price. It’s very competitive and I’m sure it would not disappoint you. The O2+ODAC Combo got my vote and it deserves The PC Enthusiast’s Highly Recommended Award.

thepcenthusiast editor's choice award

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