The JDS O2/ODAC is available from the JDS Labs homepage and the price at the time of this review was $279 in the default configuration (more about customized options and prices later).

https://www.jdslabs.com/products/48/objective2-odac-combo-revb/

I’m not in any way affiliated with JDS Labs.

Short introduction to JDS Labs: JDS Labs makes high quality DAC’s, headphone amplifiers and cables. They are based in Collinsville, Illinois, USA.

This is what they say about themselves on their website: “We go above and beyond American manufacturing. We built our in-house machine shop and production line to achieve product quality that we're proud of. JDS Labs's success comes from our obsession with brilliant audio engineering. Performance of our amplifiers and DACs pushes the market forward.

During product development, we utilize a PrismSound dScope Series III audio analyzer to conduct professional sound quality benchmarks. An audio analyzer is capable of generating reference quality audio signals and measuring the resulting output of an audio device under test. This allows us to perform impulse response tests, fast-Fourier transforms (FFTs), and continuous-time analysis in order to observe specifications which directly impact audio quality. In simplest terms, an audio analyzer generates exceptional audio signals and checks to see how closely a tested device compares to its own quality.”

About me:

I’m a 44 year old music and sound lover that changed my focus from speakers to headphones and IEM’s about five years ago. At that time I realized that it wasn’t realistic for me to have all the different setups that I wanted and still house a family of four children and a wife so my interest turned first to full sized headphones and later also IEM’s.

My preferences are towards full sized open headphones and I believe that also says something about what kind of sound signature I prefer (large soundstage in all directions, balanced and organic sound).

My music preferences are pretty much all over the place (only excluding classical music, jazz and really heavy metal). My all-time favorite band is Depeche Mode although I also listen to a lot of grunge/indie, singer/songwriter/acoustical stuff as well as the typical top 40 music.

I tend to value function over form within reasonable limits.

I do not use EQ, ever.

I’m a sucker for value for money on most things in life Head-Fi related stuff is no exception.

Built, accessories and functionality: The JDS Ojective2+ODAC Rev B are a solid state headphone amplifier, DAC and pre-amplifier (optional) combo.

In my opinion the O2/DAC is already a classic piece of equipment in the headphone related world in the same way as the Beyer DT 7/8/9XX, AKG K/Q7XX or Sennheiser HD6X0. They’re all known for offering excellent performance for money. The O2/ODAC is an open source design so anyone with some soldering skills could build one but there are also a number of half-baked sets and also fully finished options like the one JDS Labs are selling. I’ve read a lot about the O2, ODAC and O2+ODAC for several years now so naturally I was super happy to finally be able to hear it for myself.

The O2/ODAC is available in two different colors: black and silver. I’ve got the black version. It’s also customized to some extent and you can choose to power jack in the back (+3$) instead if in the front, a 6.3 mm headphone output instead of the 3.5 mm one (+$30) and/or you can chose to add a dedicated DAC output as either 3.5 mm (+$3) or 6.3 mm (+$17) jack.

The rated output power of the O2/ODAC is 613mW at 33Ohms.

The JDS Ojective2+ODAC Rev B have a metal/aluminum chassis that feels really solid. The physical controls available on it do also feel very reliable. The physical controls sums up to a volume knob, a switch to choose between how or low gain and an On/Off switch.

The JDS O2/ODAC offers one USB mini digital audio input and one separate AC power input. It also offers an analog 3.5 mm audio input and, as already mentioned, for a few dollars extra you can also add a DAC output in the back. There’s also a headphone out socket.

Unfortunately I’ve not been able to make the O2/ODAC to work with any of my Android devices. My guess is that the USB driver is too old to be prepared for this.

The O2/DAC support all popular file formats for audio up to 24bit/96kHz files. The lack of support for higher sampling rates as well as the lack of support for DSD files are probably signs of the design of the O2/DAC being several years old by now.

The accessories included are: 1 USB cable (USB A to B Type, 1.5M) 1 User's Manual 4 rubber feets 1 Power adaptor (AC 15V)

The specs:

DAC PERFORMANCE Freq. Response 20Hz-20kHz +/- 0.04dB THD+N 100 hz -0.15 dBFS 0.0028% THD+N 20 hz -0.15 dBFS 0.0015% THD+N 10 Khz -0.15 dBFS 0.0024% IMD CCIF 19/20 Khz -6.03 dBFS 0.0015% IMD SMPTE -6.03 dBFS 0.0015% Noise A-Weighted dBu 24/96 -103 dBu Dynamic Range (A-Weighted) > 112 dB Linearity Error -90 dBFS 24/96 -0.08 dB Crosstalk -10 dBFS 100K 3.5mm -86.40 dB USB Jitter Components 11025Hz -112.3dB Maximum Output Line Out 100K 2.1 VRMS Distortion < 0.005% DATA SUPPORT Audio Formats 16/44, 16/48, 16/88.2, 16/96, 24/44, 24/48, 24/96 Interface USB, Audio Class 1 Native Driver OS Support Windows XP & Later, OS X x86, iOS, PS4, Linux DIMENSIONS Case Dimensions (mm) 108.50 x 80.00 x 29.50 Case Dimensions (in) 4.27 x 3.15 x 1.16 Weight 11oz AMPLIFIER PERFORMANCE Frequency Response 20Hz-20kHz +/-0.1 dB THD 1 Khz 150 Ohms 0.0016% IMD CCIF 15 Ohms 0.001% IMD SMPTE 0.002% Noise, A-Weighted -105 dBu Max Output (33 Ohms) 613 mW

Max Output (150 Ohms) 355 mW Max Output (600 Ohms) 88 mW Output Impedance 0.54 ohms Crosstalk (15 ohms) -65 dB Channel Balance (50% volume) 0.6 dB CONFIGURATION Gain 1.0 and 3.3x

Volume Potentiometer Taper Alps 15A or 3B CONNECTIVITY Analog Output 3.5mm or 6.35mm* Analog Input 3.5mm Digital Input Mini-USB DAC Line Output 3.5mm or RCA** Power Input 14-20VAC * Denotes Customization Option ** See Jack Configurations below

The O2/ODAC has been with me for alomst two months now and it has played well over 50 hours.

Demolist:

Mark Knopfler – Sailing to Philadelphia Røyksopp (Feat.Susanne Sundfør) – Save Me Ane Brun – These Days Michael Jackson – Dirty Diana Metallica – Die Die My Darling The Peter Malick Group – Immigrant Eva Cassidy – Songbird Thomas Dybdahl – A Lovestory Norah Jones – Don’t Know Why Celldweller – Unshakeable Jack Johnson – Better Together Seinabo Sey – Younger (Kygo remix) Dire Straits- So Far Away Björk - Moon Lupe Fiasco - Deliver Morrissey – Earth Is the Loneliest Planet

Sound impression: The first thing that I noticed when I started to listen to the JDS Ojective2+ODAC Rev B was that it was less analytical and fuller sounding compared to what I was expecting.

This review will mostly be about the O2/ODAC as a DAC/amp combo but before I start on that I’d like to make a very short comment about the O2/ODAC as an amplifier only. As far as I know the original design for the O2 was for a headphone amplifier only and the goal for it was to have a completely transparent and neutral presentation. When I hooked up the bit Opus

1 DAP to the 3.5 mm analog input on the O2/ODAC the sound is indeed pretty much unaltered in comparison to listening straight from the

1. This is quite impressive and exactly what a well deigned amplifier should do. This leads me to believe that the “signature” I hear from the O2/ODAC is actually that of the DAC section. So let’s continue to explore how it performs as a DAC/amp combo.

Bass extension and impact is very good without any noticeable roll off in the lower frequencies. Sub bass and mid bass interact seamlessly with equally good quality and similar quantity making the whole lower frequencies very fluent. The combination of great bass quality and a natural quantity makes the presentation dynamic and very easy to like.

The midrange is liquid and smooth with plenty of details. The O2/ODAC sounds very linear through all frequencies and the midrange is no exception. Nothing really stands out and it sounds very natural and dynamic. I feel as if there’s some air missing from the sound though making the overall presentation a bit on the intimate and even closed in side. The sound is natural sounding and I do find that vocals is very well reproduced with enough wright on male ones and no fatigue with female ones.

The treble is well extended but does lack some air and I’m not able to detect any harshness whatsoever in it. Being slightly on the warm side it does never feel harsh or artificial to me but rather full and natural.

The overall presentation has good soundstage but better depth than width and height. Layering is also good but I do sense some lack of air between the instruments. The background does feel black and calm but the overall presentation is still a bit on the intimate and closed in side. Transparency is also quite good and all together I’d describe the sound of the O2/ODAC as slightly warm with great dynamics. This is a signature that I personally find to be quite enjoyable paired with most IEM’s and headphones.

Comparison: Please note that the comments in the comparison section are not in absolute terms but in comparison between subject A and B. This means (as an example) that if subject A is found to be brighter than subject B it does not necessarily mean that subject A is bright sounding in absolute terms. I hope this makes sense.

In these comparisons I’ve been listening through my Hifiman HE400i’s.

I’ve been using the USB input when doing these comparisons. Both units has been hooked up to two different laptops both running Windows 7 with the same settings and I use MediaMonkey as my player of choice.

Both units was connected to a simple switch box through their respectively headphone outputs. This way it’s very easy to switch between the sources in minimal time. I also use a simple Android app to volume match the amplifiers so although maybe not perfectly scientifically the result should still be pretty correct.

Burson Audio Conductor V2+ (1,499) vs JDS Labs Objective2+ODAC Rev B: Compared to the V2+ the O2/ODAC is more closed in and intimate sounding while the V2+ is more much more airy and has better timbre to the notes. The O2/ODAC is overall darker and also a bit duller in its presentation. The V2+ has a larger soundstage width and an overall more relaxed and effortless presentation.

The V2+ of course has some other advantages as well such as significantly higher power output (4W @32Ohms compared to ca 613mW@33Ohm on the O2/ODAC), two analogue RCA inputs and both pre-amp and DAC direct RCA outputs, in addition it also has a great quality remote control.

Although both these are well build the V2+ definitely has a better build quality and should also have so costing about five times the price of the O2/ODAC.

Cambridge Audio DacMagic Plus ($499) vs JDS Labs Objective2+ODAC Rev B: Compared to the DacMagic Plus the O2/ODAC has an overall sligh fuller sound. The ODAC offer more energy and attack while the DacMagic Plus, albeit being a touch brighter, is more relaxed and laid back. The ODAC is more distinct in what it does and has better clarity while the Cambridge is smoother and had noticeable more air between instruments, this is also the reason that it feels more relaxed in my opinion.

Feature wise the DacMagic Plus offers both coaxial and optical inputs in addition to an optical output. The ODAC has a 3.5 mm analog input while the DacMagic has both RCA and balanced outputs. The O2/ODAC is considerable smaller and both units feel very well built.

iBasso D14 “Bushmaster” ($249) vs JDS Labs Objective2+ODAC Rev B: Compared to the O2/ODAC the D14 have a lighter and less dynamic presentation. The D14 is definitely the brighter sounding of the two while the O2/ODAC is warmer and more dynamic but also more congested. The O2/ODAC does also offer more energy and attack. The treble on the D14 is more airy and has better extension. Overall the iBasso unit is cleaner and leaner with a wider soundstage while O2/ODAC is more dynamic and warmer sounding.

Feature wise the D14 offers both optical and coaxial inputs. They both have 3.5 mm analog inputs but and gain switch. They both have USB mini inputs and 3.5 mm headphone outputs (the O2/ODAC can be customized to 6.3 mm if wanted). The D14 can also run directly from USB power as well as on battery which makes it more flexible. The footprint of the D14 is quite a bit smaller. Build quality feels very solid while the O2/ODAC packs a bit more power.

For even further comparisons feel free to visit this thread for breakdown between more $250+ amp/DAC units (this is a work in progress and several other units will follow in the near future).

Matching: The output impedance of the headphone output on the O2/ODAC is rated to a very low 0.54Ohm. This means that it should work really well with pretty much every pair of headphones and IEM’s out there.

In this section I’ve tested how some of my favorite headphones but also one earbud and one pair of IEM’s pairs up with the O2/ODAC.

Hifiman HE400i ($449): The HE400i, when paired with the O2/ODAC, has great drive and dynamics making it sound quite engaging to me. The HE400i doesn’t have the widest stage and neither does the O2/ODAC but they still work very well together making for a non-fatiguing and toe tapping listening experience.

AKG Q701 ($300): The Q’s sound good paired with the O2/ODAC in my opinion. The bass has good presence and impact, which indicates that the power is sufficient. I find the overall sound slightly on the warm side and this suit the Q’s quite good. Although this combination doesn’t sound bad I’ve heard better sources for the Q’s.

Philips Fidelio X2 ($300): The X2’s has plenty of dynamics on its own and can sound a bit too bassy and boomy when paired to a warm source that have more than the natural bass presence. With the O2/ODAC it sounds full and engaging, retaining its great dynamics without getting overly boomy. This pairing is very good in my opinion.

VE Zen 2.0 ($138): The Zen 2.0 is a 300Ohm earbud that I like a lot and tend to use instead of closed headphones.

The Zen 2.0 has a smooth and pretty laid back signature that works fine well with the O2/ODAC. There’s enough energy and dynamics to make the presentation engaging and easily enjoyable. I’d say that this is a very nice combination.

Aurisonics ASG-1PLUS ($500): The ASG-1PLUS is an 11Ohm hybrid IEM (1 DD + 1 BA).

The 1PLUS has an excellent out of head presentation and its bass (especially mid- and upper bass) is quite a bit subdued. I’d say that they work fine with the O2/ODAC. There’s enough dynamics to be enjoyable will all kinds of music but the overall presentation get a bit on the dull side. This is still an enjoyable combination though. Although the 1PLUS is not as easy to drive that the 11Ohm suggest I’m not able to detect any background hiss whatsoever when using them with the O2/ODAC.

To sum up the matching section the signature of the O2/ODAC does make pretty most of my headphones and IEM’s sound very good and I haven’t come across anything that pairs badly with it. The O2/ODAC has a very low amount of audible hiss even when paired to my most sensitive IEM’s. The O2/ODAC does also have enough power for all my full sized headphones which makes it very versatile in practical use.

Summary: The JDS Ojective2+ODAC Rev B may be a bit old in its design and not offering support for the latest and greatest high definition audio formats but in my opinion it still holds its own even in today’s crowded market. It offers USB audio in as well as an analog input and is also partially customizable upon ordering. I’d also like to add that while the O2/ODAC is a good amp/DAC combination, although it may lose out in overall performance against more expensive offerings, it is an amazing amplifier delivering a truly neutral presentation just the way a great amplifier should. So if you’ve got a great quality source already the pure amplifier version of the O2 may be a better, and cheaper ($129), option.

Priced at around $300 (depending on configuration) the JDS Ojective2+ODAC Rev B may not punch way above its price point anymore but I’d still consider it a valid option within its price bracket. It doesn’t support DXD/DSD but if that’s not a big deal to you and you value a fairly neutral and very natural sound I’d still recommend looking at this classic piece of equipment if you’re on the hunt for a new partner for your computer or laptop.