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Desktop Amps item created by USAudio, Oct 28, 2012
Pros - Sound quality, build quality, customizable, fantastic amp section
Cons - Dosen't support the highest bitrates, amp section stronger than the DAC section
This is a review of the JDS Ojective2+ODAC Rev B amplifier and DAC combination.
The JDS Ojective2+ODAC Rev B (O2/ODAC) was sent to me for free by JDS Labs for the purpose of doing this review and including it in my recently started $250+ amp/DAC comparison thread. A big THANK YOU to JDS Labs and Jude for letting me check it out.
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).
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.”
Spoiler: Click to show!
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)
Spoiler: Click to show!
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%
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
Case Dimensions (mm) 108.50 x 80.00 x 29.50
Case Dimensions (in) 4.27 x 3.15 x 1.16
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
Gain 1.0 and 3.3x
Volume Potentiometer Taper Alps 15A or 3B
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.
Spoiler: Click to show!
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
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.
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).
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.
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.
Audio Quality: 4
Pros - Small, Transparent, Open Source, DIY Capable
Cons - Outdated
Intro: JDS Labs, Is an American company based in Collinsville, Illinois. They make headphone amplifiers & DAC’s. Mr. John Seaber is the man behind JDS Labs. We might remember JDS Labs when they produced the popular cmoy-BB amp & later on, their Objective2 which was a game-changing amplifier. JDS Labs also have their own products: C5/D Portable amplifier/DAC, Element desktop Amp/Dac along with their Cmoy BB amp. My profound thanks to Mr.John for arranging a sample unit for my evaluation.
JDS Labs O2 was my first ever headphone amplifier in early days of my Head-Fi days. Enjoyed it a lot, had a wonderful time with it. O2 holds a special place in my ears.
About O2/ODAC: The Objective2 as we all know, is a very famous beginner level amplifier, has a very neutral sound signature. Few years ago there were not many amps available under a budget. The one’s available didn’t perform good. O2 was designed by a U.S electric engineer “NwAVGuy” in 2010-2011. The O2 amp standalone is portable & battery operated. But take out the battery & you can fit a tiny DAC inslide the same enclosure called ‘ODAC’.
ODAC is the DAC counterpart of the famous O2 amplifier, & was released in 2012. The ODAC was jointly developed by NwAvGuy and Yoyodyne Consulting . Yoyodyne generated ODAC’s circuit board, and NwAvGuy provided performance analysis. Yoyodyne has remained responsible for all production engineering & distribution. ODAC was certified as Objective by NwAvGuy; Yoyodyne generated the design and controls its manufacturing. The new Rev.B uses SA9023 & PCM5102A, and the Low dropout regulator has been updated to a ceramic stable Analog Devices ADP151 equivalent part. Fixes include: Added 16x vias to USB support pads to improve mechanical strength of mini-USB jack, new improvised circuit board & locked EEPROM to prevent IC failures, fixed USB supply stability, & minor performance improvements. Rev.B now puts out 2.1VRMS power.
Packaging & Accessories: The unit comes packed in JDS Labs stamped strong black cardboard box. It withstood a rough journey across the globe, yet remained in perfect shape. That explains everything. Included accessories:
Power Adapter: 15V AC-AC adapter. The AC-AC adapters help in minimizing flux leakage in the circuit.
USB Cable: Mini USB cable with ferrite bead, Monoprice brand, has very good quality with 28+1P/24+2C AWG gauge, matches very well with ODAC.
Design and Build: It has an aluminium case, & the unit which I am reviewing is the RCA version (with RCA connection for ODAC) The RCA jacks being connected to ODAC via soldered wires. The device itself is very small, nimble & has small footprint. Can also be used as portable DAC, as it is self powered. It does not require any drivers & works on low current draw, which is a plus for compatibility with portable android smartphones. Another advantage of O2/ODAC is, you can build one right in your home using basic soldering tools. It's DIY Friendly.
Sound: Both O2 & ODAC are well documented with scientific proofs about the accuracy of sound delivery, so no questions about that. It delivers whatever is fed into it’s system. Using neutral headphones like HD800 or K702 makes the experience bitter due to harsher treble, but with darker sounding headphones like LCD-2, O2/ODAC does a good job. Driving power is fine, though not as powerful as desktop amplifiers. Op-amps can be swapped for a different hearing experience. Take out the 2068D & install a compatible op-amp of your choice.
Comparison: I would like to compare the O2/ODAC with Schiit Magni2/Modi2 which costs under 200$. Schiit has improved the original Magni & Modi, now the reliability & sound quality is noticeably better than the original version. Both Magni2 & Modi2 outperform their counterparts O2 & ODAC Rev.B respectively. Modi2 is much more accurate than ODAC plus an added advantage of 24/192 capacity. Modi2 also sounds much cleaner, clearer than ODAC. Magni2 is more powerful than O2 and also delivers higher transparency. As combo, Magni2/Modi2 outperforms O2/ODAC. Schiit combo costs 200$ with additional features & better sound quality, hence Its a value for money deal.
Affordability: The truth is, O2/ODAC is losing its charm it had few years ago. This is due to tough competition from modern & advanced products with latest designs. Had been NwAVGuy still around, he would have definitely continued developing the O2/ODAC . But sadly he has disappeared from audio community since long back. So I have to conclude that O2/ODAC is now outdated, and as a replacement, Schiit stack serves the purpose under 200$ budget. The O2/ODAC costs about 275$, which is significantly higher than the Schiit combo.
Conclusion: O2/ODAC though once a benchmark for performance, is outdated. But it still delivers what it was designed for: “Objective Approach with no BS”. O2 & ODAC created tough competition & compelled audio companies to develop affordable devices with much more value to customer’s money. O2/ODAC will slowly fade away, but will always be remembered as the Game Changer.
My tribute to NwAvGuy: The Man behind the Change.
Pros - Transparent, Powerful, Compact, Audibly Silent, Reference Grade Performance
Cons - Aesthetically challenged in some respects, No RCA in or out,
The JDS Labs O2 + ODAC combo (and just about every other version) is built into a simple metal enclosure (mine is black) and all of the inputs and outputs, save for the USB input are located on the front of the device. Aesthetically, I don’t love that design decision but I understand it’s one that was likely made due to the O2 being designed originally as a portable (sort of) amplifier, not a dedicated desktop amp.
So the aesthetics aren’t that great but functionally; I don’t take issue with it. In fact, I’m more than pleased with its performance. Besides, I’m not buying audio equipment based on aesthetics; I’m buying it based on performance. And oh boy can the O2 perform. There are certainly prettier amps out there but amps that can perform as the same level as the O2? Well, probably not in the same price range.
First off, this amp is dead silent. Even with my Creative Aurvana 3 IEMs, the most hiss-prone of all the IEMs I own, the O2 is completely silent. Very impressive.
But the best thing about the O2 + ODAC is how they don’t offer any of their own color to the sound. The two of them disappear completely from the signal chain, allowing you to hear your headphones like you’ve probably never heard them before. If you plug in a pair of HD 600s, the O2 + ODAC will sound like the HD 600. The same goes for the ATH-M50, Triple.Fi 10, RE-262 and just about every other pair of headphones and earphones you can think of. The O2 + ODAC are entirely colorless and transparent, allowing for the sonic characteristics of the headphone that’s plugged in to shape the sound.
And that’s what a good amplifier should do, in my opinion, tube amps obviously exempted due to added coloration inherent to their design. A good amplifier should provide ample amounts of power or current to power hungry earphones without altering the sound itself. That’s what the O2 + ODAC does.
But before you rush out to buy an O2 + ODAC, thinking they’ll make your headphones sound better, keep in mind what I said before about them being transparent. The O2 + ODAC aren’t going to magically make your iPod earbuds sound amazing but they will allow for just about any headphones or IEMs to reach their full potential. Though some earphones and headphones are easy enough for an iPod to drive on its own, high impedance ‘phones like the 150 ohm RE-262 and 300 ohm HD 600 need the extra power provided by a dedicated amplifier to sound best. That’s what the O2 does. It doesn’t make headphones sound better; it helps them sound as good as they’re supposed to.
A word of warning though. I keep harping on the transparency of this setup for a reason. Namely, the old adage of “garbage in, garbage out” still applies. If your music collection is filled with crappy 128kbps MP3 files you’ve…”obtained” over the years, this amp will not make them sound better. If anything, it will make the flaws even more obvious. Provided you have good enough headphones, of course. But then again, if you’ve got good headphones, I’d imagine you’d be cognizant enough to make sure your music collection is up to snuff.
But I’ve been wrong before.
Anyway, this is a well built, well thought out and high performing amplifier. I’ve got to hand it to He Who Must Not Be Named on Head-Fi (Not Voldemort), as he talked the talk and proved he’s got the engineering chops to walk the walk. The O2 + ODAC is about $300 fully assembled and shipped or $150 each individually (and the stock O2 has the ability to function as a battery powered “portable” amplifier) so they’re a bit pricey for most people but for music lovers, this is an investment that will pay off in spades every time you hit play.