iFi iPurifier 2

General Information

It is an Asynchronous Active USB Purifier Hub. It offers 100X to 100,000X noise reduction for USB Power, underpinned by REclock®, REgenerate® and REbalance®. It is an active USB hub and is used at the end of the chain. It will become available in type A, B , C or micro USB connector version for a wide array of USB audio devices.

Latest reviews

Pros: Greatly reduced noise, blacker background, added transparency
Cons: None!
    When it comes to Audiophiles, our number 1 goal is to achieve perfect audio transparency. Along our journey towards audio nirvana many of us, myself included, have met the snake oil salesman. With his promises of “enhanced resolution”, “deeper lows”, and “crystal clear highs” he preys on our weakness. Some of us move on, and some of us walk away with an armful of boa-thick USB cables and VCR sized power cleansers. While there are products out there that actually meet their claim, weeding out the good vs the outright deplorable can be daunting. As the saying goes, “ Once bitten, twice shy… “. So when it comes to the iPurifier2, what makes it any different than any other product and their “claims”? It’s simple; iFi Audio and their reputation!
    The iPurifier2 was sent to me direct from iFi Audio USA in exchange for my impressions and review. The words I write are my own and are honest, objective, and free of bias. I received no financial compensation for my effort, only the satisfaction of trying out a quality product for a few weeks.
    I would also like to thank Lawrance over at iFi Audio. He had originally contacted me in regards to reviewing the new iTube2. Unfortunately (for me) sales and demand were higher than expected leaving no units available to send out for reviews, and I was asked if there was any other product that I was interested in to tide me over until re-stocking. I have always been both a believer and a critic/skeptic towards, generally speaking, cleaning up the noise from a digital audio signal, so naturally I chose the iPurifier2.
About Me
    38 years old, I grew up in a family consisting of musicians, broadcaster/sound engineers, and amateur DJs, I always had a deep appreciation and understanding of both music and sound. I was further educated in this self interest after taking courses in both basic electronics and Sound: Electro-Acousto aka The Path to Golden Ears. While I believe a listener’s preference in sound is subjective, the science behind it is not. I am not swayed by buzzwords, hype, trends, brand recognition, or big numbers on charts; I am the nemesis of the commissioned salesperson. Opinionated as I am, my words are not only objective but honest. I view all criticism as constructive, as long as it is sincere. 
    If one is familiar with my other reviews, you are aware that I am a huge fan of minimalistic yet functional packaging that gives the consumer the sense that they have purchased a quality product, and the iPurifier checks off all boxes on the list. Much like iFi’s other products, the iPurifier2 comes in a white, almost Apple-esque sturdy box. The device is nestled in foam with the contents neatly packaged in; There is no wasted space holding nothing but air, rather only what is needed. In terms of what you get, it’s not much, and not surprising considering the iPurifier is a USB powered dongle. Besides a feature card with warranty information on the flip side, all that is included is a female to female USB type A/B converter (not pictured because seriously, we all know what it looks like).
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- Aircraft grade CNC-aluminium shell anodized in titanium
- Active noise cancelation forged from military radar technology 
- EMI/RFI filtering
- REclock® reclock/regenerate/repeat
- REbalance®
- Gold plated plug/jack
- USB Type A, B, C, or micro
- Future-proof technology compatible with all existing audio formats
By generating a signal identical to the noise signal but in the exact opposite phase, it actively cancels all the incoming noise. ANC® is the perfect ‘antidote’ for power supply noise, the bane of USB audio. 
ANC® measured, noise drops by 100 times or 40dB in comparison to the Common Noise Filter. Sonically, the background and inner resolution to recordings is enhanced several levels. 
REclock® reclock/regenerate/repeat the signal 
Re-clocking is beneficial to audio. REclock® is a ‘3-in-1’ feature that re-clocks/re-generates/repeats USB audio data-stream. For any and every downstream DAC, REclock® technology eliminates jitter. Music flows better, is cleaner, deeper and tauter, just like the real thing. 
REbalance® rectify the unbalanced signal
A core element of the original iPurifier’s success was REbalance® which has naturally been carried over to the iPurifier 2. By removing the DC offset and ‘re-balancing’ the USB audio signal, it is now perfectly balanced. As it purifies the USB audio data stream, this means noise is significantly reduced:
    Similar to most of iFi’s products, the iPurifier2 features a shell machined of CNC-aluminium and is held together by 4 screws. Unlike it’s predecessor, the iPurifier2’s case is anodized in titanium, giving it a darker tone overall. I actually like this as it helps make the device less noticeable. With the dimensions being 62(l)x19(w)x18(h)mm, the device itself is around the size of a standard USB dongle meaning it shouldn’t interfere with the connectivity of the other cables adjacent to the USB port nor should it be too obtrusive when added into the chain. Of course, YMMV. Both the USB plug and jack are gold plated and are of good quality; Both the plug and jack fit snugly with their respective mate. A blue light illuminated when power through the USB cable is present, and a green light indicates that the device is connected to the DAC.
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Why it’s needed -  A summary from the pros
“ Electromagnetic interference (EMI) is an electromagnetic emission that causes a disturbance in another piece of electrical equipment. EMI can be attributed to a wide span of the electromagnetic spectrum including radio, DC and even microwave frequencies. Because anything that carries rapidly changing electrical currents gives off electromagnetic emissions, it is quite common for one object’s emissions to “interfere” with another’s. EMI compromises the performance of electrical equipment by obstructing and degrading data; sometimes even losing data completely. PCs can be affected by electromagnetic interference from other devices, in two major ways. One is direct effects through proximity with other devices; another is electrical interference over the power lines.
“ The most significant way to circumvent the shortcomings of mass-market computer products is to minimize power supply noise. When power supply noise is minimized, the result is cleaner and more defined “square waves” in the digital signal, which translates to fewer bit read errors, less error correction, and less jitter. “
Playback jitter originates from a large number of contributors, which are usually additive. These range from the master clock, which has its own jitter, to logic devices, to mechanical systems for spinning a CD. One digital cable can even add more jitter than another. Each contributor adds more jitter to the signal as it makes its way to the D/A converter. This summation of this jitter is the system jitter. “
Thoughts and Impressions
Before I continue, my thoughts and impressions in this section of the review will be generalized. During my time with the iPurifier2 I used many different headphones, audio sources (movies, music, games), and hardware, and listing off impressions of them all would be both an exhausting read, let alone write.
As mentioned earlier, I am both a believer and skeptic of cleaning up a noisy digital signal. My beliefs stem from real world experience working in high-tech manufacturing. I have spoken with engineers working out of multi-million dollar, shielded test labs, and can say with 100% certainty that noise, especially digital noise not only is real but the bane of their profession. The skeptic in me, like most of us, was born out of many manufacturer’s claims basically stealing my money with little to no return. Never trust anything in a starburst folks! Needless to say, I was going in with an open mind. 
Having gone though great lengths to reduce my perception of noise, coupled with iFi’s reputation for quality, I had high expectations for the iPurifier2 going into this review. My daily-driver set-up includes the micro iDAC and micro iCAN SE with iPower 15V connected via shielded solid core OFC RCA, DIY separate shielded data/power USB cable with 3 ferrite chokes on each plug, dedicated isolated USB bus, power bar with “clean power”/ 2.0A USB/  EMI/RFI filtering (up to 40dB)! Overkill? No way! I can say with complete conviction that every last piece is needed! So did the iPurifier2 make a noticeable difference? Depending on the situation, yes!
The first noticeable “purification” came in the form of overall noise reduction. As the saying goes, “you never notice it until you hear it” or in the case of the iPurifier2, “you don’t hear it”! Without a shadow of a doubt, the amount of noticeable EMI noise reduction was more than subtle. It mattered not if open or closed back, IEM or circumaural, I noticed not only a substantial amount of hiss and buzz reduction but a much blacker background as well! The blackness was very much akin to listening to a high-end battery powered Digital Audio Player (DAP).
Further listening proved to be full of surprises, ones that I was not expecting. For starters, dynamics and subtleties of certain source material gained an increase in focus and resolution. Whether it be a trio of guitars, an action packed scene from a movie, or the sense of breath from a vocalist, everything seemed more textured, detailed, and easier to discern with the iPurifier2 in the chain. Both the soundstage and imaging were increase as well with a much greater sense of space and speed. It is almost like an invisible veil has been lifted, allowing the sound to fully bloom. Then there is the smoothness, perhaps the biggest surprise. It’s hard to explain, but the iPurifier2 has an overall less jagged, less digital quality, instead giving a sense of a more analogue and natural fluidity to the sound!
micro iDAC with standard USB cable -  This is what I consider the most likely use for the iPurifer2; Computer to DAC with a built-in headphone amp via USB2 asynchronous protocol. Regardless of connecting to a stand-alone USB port or the front panel header the iPurifier2 worked it’s magic and noticeably improved the clarity and transparency of the signal. With the volume pot turned to full, the amount of audible noise was reduced to basically nothing. Dynamics were not only increased a notch or two (depending on the source) but sound more rounded and less sharp and jagged. Imaging and focus became more clear and apparent, especially when it came to subtle background sounds (i.e. rustling of leaves, shakers and tambourines). While it is difficult to tell if the iPurifier cleaned up any issues with the USB protocol, it definitely “purified” the EMI/RFI noise coming down the chain, peeling away a few layers of invisible grain!
Sharkoon USB DAC/Amp - StarTech, Vantec, Skarkoon, It matters not what vendor this guy came from, I am sure most of you folk reading this have seen some variation on this 16/44 small 1” silver USB dongle. It’s cheap, it’s basic, and I purchased mine for $4 to use if I am ever in a pinch. The purpose of me including this DAC/amp in my testing was to highlight how well the iPurifier handles what I consider a worst case scenario, and I am please to say it exceeded my expectations! Straight out of any USB port this little guy manages to seemingly pick up every bit of electronic noise coming from my system. I move the mouse I hear noise. A hard disk spools, I hear noise. I hear the hum of what I can only assume are the 10 case fans. And then there are the random pops and clicks. With the use of an adaptor, adding the iPurifier2 into the chain was like night and day! It was as if I had my headphones plugged into my iPod! While it was not 100% black (pretty close though), all the computer generated noise was completely gone; No more random pops and clicks, no more hum or hiss! It’s hard to say how much the iPurifier2 added to sonic transparency, being a $4 DAC/amp and all, and I find it absolutely laughable that anyone would ever use these two devices together. For comparison, I connected the DAC using only my DIY USB cable aforementioned on a dedicated bus. While the cable did alleviate some noise, it was no where near the same level as the iPurifier. My DIY cable performed as well as a a standard USB extension cable with a single ferret choke, and I am certain half of the noise reduction was from moving the DAC away from the source/cause of the noise.
micro iDAC and micro iCAN SE with iPower 15V (my daily driver) -  With a setup like this, would adding the iPurifier2 even do anything? Absolutely! However I must admit that any changes were considered more subtle, yet still noticeable. Only at higher volume (with 24dB gain) did I hear any reduction in audible noise. In terms of improvements in dynamics, I hear less compared to the first two scenarios, although the signal once again did sound more rounded and less sharp/jagged. In this situation, the iPurifier2 did indeed improve my listening experience, and I don’t want anyone to take away from this as being “not value added” simply because the improvements were not as apparent as the other situations. To my ears the iPurifier2 performed admirably.
    When it comes to transparency, I like to say every little bit counts no matter how small of an improvement one may hear. Taking into consideration the performance coupled with it’s high quality construction, at a price of $109 USD the iPurifier2 is a very cost effective way to increase the fidelity of your USB audio no matter if you are an audiophile, enthusiast, or simply someone who hears too much garbage coming from one’s PC.
Since moving from playing music on a CD player to digital audio stored on a hard disk drive, I found myself in the seemingly endless battle of reducing noise and restoring transparency. Noise creeping into the digital signal is a real problem, one that iFi-Audio both recognizes and addresses. My time with the iPurifier2 wasn’t so much of an eye opener as it was a confirmation. While all systems will benefit to a degree from adding the iPurifier2 into the chain, undoubtedly some will yield better results than others. In my opinion adding the iPurifier2 into your audio chain is a no-brainer if one desires the absolute best in audio performance. I know what my next purchase is going to be!
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Great review, thank you. I have the first iPurifier, is it worth upgrading?
Robert Padgett
Robert Padgett
The iPurifier 2 is a must have accessory, no matter what system it is used with. As "Computer Audiophile on the Cheap" it is the best $109 I have spent.
@Rearwing Apologies for the late reply. I would say yes, simply because of the added features such as ANC and ReClock. $109 isn't a lot to spend and I am sure you could recoup the cost by selling the original.
Pros: Well built, choices of different connectors
Cons: Colorations
i actually won the ipurifier 2 in a contest, and as a pure enthusiast I would like to voice up what I gathered under different instances and circumstances. The ipurifier is very well built and eyes catching. It offers different kind of connectors end to be ordered by your liking and convenient.

Using HA-1 and Zx2-Cradle with all lossless, high-res, and DSD albums. I observed the following instances.

1/ out of the box, stock everything. The ipurifier 2 offer immediate improvements as in bigger bass, dynamic, punches, and some trebles details, larger images and spaces

2/ with real upgraded USB cables, the Ipurifier 2 shows up as a coloration device. It boost the bass and trebles while veiling up the very fine micro details in both sub-bass and lower-trebles.

The experiences were rather strange for me, but I came to a conclusion that the Ipurifier is neither negative or positive. It depends on what you have in your system. From a good system, and stock USB cables, the Ipurifier 2 is positive. But if you have "real audiophile" upgraded USB cables, it will be rather negative.

Now, when I meant Audiophile Grade USB, I literally meant it. The cables where you observe the changes and improvements right immediately compare to stock.

However, USB cables of real audiophile quality is really not out there yet, and or unless you spend a hefty sum on it. Then we are speaking audiophile USB grade. In my experiences, I use my own DIY USB cables and was able to observe the above. I guess to the majority of folk out there, the Ipurifier 2 should be a positive device within your chain.
Pros: Focus Clarity and increased resolution added to your audio tracks
Cons: None
The current widespread diffusion of liquid music, a kind of new word adapted to indicate the usability of music via media, such as music files in MP3, PCM or FLAC format has generated an increasing number of devices and appliances that use the USB protocol for audio transmission. In this regard, if we really wanted to be picky, the USB standard was not developed for the transmission of digital audio, but over time has attracted growing interest from nearly all brands of hifi equipment such as DAC, Media center etc, given that every home now has a computer.
The increasing use of a computer, be it a Mac or PC, as a source for streaming music has placed the USB connection at the top of the list of the digital protocols used to stream music over standards such as S/PDIF (coaxial digital) or the AES-EBU (balanced digital) linked now more to the professional sphere than to the consumer one. However, the transmission of digital data via USB is far from perfect, especially when compared to the previous protocols and when the source of transmission of the music is a computer that represents an area potentially subject to electromagnetic and electrical interferences. We are talking about problems such as EMI noise which is generated mainly by switching power supplies inside a computer that incorporates a switching regulator to use electricity more efficiently. Its presence can become very annoying and easily noticeable between one song and another. For this reason, in order to be able to express its full potential in the digital audio world, the USB standard needs a series of measures that will significantly improve the sound performance. In this regard, in our previous article, we already dealt with a very interesting accessory called iPurifier produced by iFi Audio, which we wanted to award editor’s choice due to its real benefits and improvements within our USB audio chain. Recently iFi Audio has gone one step further and made the worthy successor of the iPurifier i.e. the iPurifier2 the subject of our article.
The iPurifier2, as with the first version, is sold in a tiny package that contains both a short illustrated manual and a USB signal repeater. Its external structure is made of die-cast metal with 4 tiny screws present in the upper part. On the top, when compared to the previous iPurifier, the new model has 2 LED which indicate the presence of both the power and the audio signal coming from the computer or whatever source is used. Other than this, following an initial assessment, all might seem the same as the previous iPurifier, but on reading the instruction manual we discover a new series of proprietary technologies that iFi Audio wanted to implement in this new version. We refer to ANC® or Active Noise Cancellation and three different solutions called REclock® REbalance® and REgenerate®. The Active Noise Cancellation is inspired by a technology used by the military forces. As described by iFi Audio when a radar for air defense transmits a certain frequency necessary to find the enemy, this can be picked up by a receiver on board of the aircraft that analyzes and generates an identical but reversed phase one thus neutralizing the radar signal and preventing the plane from being intercepted. Similarly ANC® technology generates a signal identical to the original noisy one, but phase reversed actively deleting all the input disturbance. This system is a very effective antidote for EMI noise that is the bane of every USB audio signal. iFi Audio claim a noise reduction of 40 dB on the input signal and a leveling from 100 mV to 5 mV on the audio band through the USB signal thus noticeably decreasing the threshold of the background noise. In addition to that, the iPurifier2 also exploits a reclocking function that’s further broken down into two phases. The first one, or the REclock® which gets along with the REgenerate® has the task of eliminating jitter as much as possible by regenerating a new synchronism into the USB signal that is independent from the one generated by the computer. The second one or the REbalance® has the function of correcting the unbalanced signal by removing the DC offset and possible inconsistencies impedance as does the original iPurifier. The term DC offset is derived from electronics and refers to a signal whose value has been moved by a certain value in respect to its reference mass. By extending this concept to the representation of a waveform, the DC offset can be considered the average amplitude of the waveform, and only when the average amplitude of this waveform is equal to zero, the DC offset is neutralized and the signal becomes perfectly balanced. Finally, compared to the previous model, the iPurifier2 has a USB 3.0 port in the back that is backwards compatible with USB 2.0 standard and allows the user to choose from 4 different kinds of sockets of the USB standard named A, B, C and the micro on the front so we have the widest compatibility with all digital audio sources on the market.
Listening Test
As usual we have inserted the iPurifier2 between our USB reference cable the Silver-One by Portento Audio and our DAC - the Tobby by Firestone Audio. We burned-in for at least 48 hours before doing any critical listening. The test took place in our small studio using our audio workstation bundled with Windows Fidelizer and JRiver as a player. To listen we used our reference headphones: the Audeze LCD-X, the HiFiMan HE-6 and the Sennheiser HD 650 driven in balanced mode by our two amplifiers the Audio-GD Master 9 and the Violectric V281. The music selection was based largely on high-resolution recordings of both rock music and electronic pop jazz characterized by a good dynamic range. One of the most interesting things about the iPurifier2 is that it doesn’t require any installation driver therefore acting as a plug’n’play device. It’s also compatible with PCM signals up to 768 kHz and DSD signals up to 24.6 MHz. Once we started the listening session the first feeling was that experienced years ago in a recording studio when we connected a word-clock outside our Rosetta converter made by Apogee. We immediately noticed, to say the least, a more general focus on the sound message thanks to the better performance of the frequencies and the transients accuracy. In electronic music tunes, where the kickdrum and bass are predominant, the percussion instruments are noted for having greater incisiveness and depth of low frequencies as if the drivers of our headphones were shaken up in a clearer and stronger way. Certainly we are not talking about overnight differences but sonically audible changes. The mid-range is the other portion of the sound spectrum that benefits more, giving back voices and guitars in a natural way and with greater presence. Regarding the high range, we can safely confirm rather less grit and a slight gain in extension. We believe that this type of improvement on high frequencies is due to a lowering of the jitter value. There’s no doubt that the iPurifier2 with these new functions such as REclock® and REgenerate® makes its presence quite evident in the USB chain and provides a more incisive performance than its predecessor. Given that we always like to experiment and exchange feedback directly with the manufacturer, at their suggestion, we tried to put a 5 volts linear power supply also produced by iFi Audio known as iUSB, between the DAC and the iPurifier2. This additional step was able to give our DAC, a USB signal that is appropriately powered in a linear manner without external disturbances. If at first we were dubious about the use of an external power supply associated with the new product made by iFi Audio, we were forced to change our mind. The inclusion of the iUSB allowed us to extrapolate power and audio data separately with the use of a Y USB cable also produced by Portento Audio. The quality of the USB signal in this new configuration has risen even further thereby improving some sonic aspects that originally had been already enhanced by the iPurifier2 in our audio chain. Finally, it also gave additional benefits to the stereo image that has become broader and better defined within the location of the instruments. The combo of the two products then took the audio quality of the USB signal to a level that didn’t make us miss what we could have achieved with two simple connections such as the S/PDIF or the AES-EBU.
Final Thoughts
Unfortunately or fortunately, and we will never tire of saying it, the USB protocol, when purely intended for audiophiles or digital audio purposes, needs a whole series of measures and additional aids in order to unleash all of its potential. The iPurifier2 is definitely one of them especially if combined with a linear power supply as the external iUSB. Together they form a powerful team that can appreciably raise the performance of your USB audio chain. For this reason, the iPurifier2 is an essential accessory for digital audio via USB. We tried many more times and on several different occasions to do without the iPurifier2 thereby making many comparisons with it active or not, but once our demanding ear was accustomed to the performance of the new product we could not go back to leaving the iPurifier2 and the iUSB out of our setup. Even if you think that we are spoiled, we think that, this is one of those few vices that ultimately it doesn’t hurt either your health or your wallet.
Personal opinion
To be honest I’ve always been rather biased towards the USB protocol for what regards the transmission of digital audio because it has often been defeated by other protocols such as the S/PDIF and the AES-EBU. It may therefore be difficult to think that what it appears to be and I emphasize "appears to be", looks like that only a small passive filter can really make a difference. But over time I have had to think again about the quality of the USB standard especially when you have the necessary tools to make it sound its best. The iPurifier2 is definitely one of them, and since the first version has really raised the quality of the performance so much so, to the point that those sensations, when first used, reminded me as I told you, of when I used an external word-clock for the DAC in my studio. Everything is much more in focus, more precise and realistic than the previous listenings. If the sound transmission via the USB iPurifier2 is already itself a step forward compared to the normal connections such as the S/PDIF and the AES-EBU and somehow brings tangible benefits sonically, the iPurifier2 joined with the iUSB is one of the definitive steps towards the top quality USB audio. Well done iFi Audio!!!
I'm dubious this can offer any benefits but if it does, since you're talking about noise levels and digital signal outputs, shouldn't it be easily demonstrable with actual signal analysis - waveforms, graphs and such? Someone needs to math the heck out of this. Intuitively it sounds as ridiculous and unnecessary as gold-plated optical cables, but I don't know everything about EMI and digital audio.
I have one myself. And yes it really improves things, but in a very subtle way. If you're not that sensitive to treble or high mid glare (with some recordings) than steer clear of this unit. Over a period of time I really can tell that recordings that have/had a tendency to get fatiguing (not ideally recorded high pitched violins) are less fatiguing with the iPurifier in the chain. It really does. The catch however is that the highs are more extended, true without hardness or glare, but if you are generally sensitive to highs than I wouldn't recommend this unit.
This is the first 'tweak' thingy I got that really makes a difference. I never could tell differences between speaker cables, interconnects, and always have a very hard time comparing sources (DACs and CD players), never could pick one as the best or as really different sounding. Maybe iFi should make a purifier for analog coaxial connections as well LOL, because MP3s played by my iMac connected to TEAC UD-301 via USB and iFi iPurifier sound better than a CD played by my Marantz CD Player coaxial connected to my TEAC DAC.
@fradoca - on your blog http://www.hdphonic.com/en/hardware/ifi-ipurifier2/ you mention at the bottom: "The measures show very interesting values" but you havn't shared those values either on your blog or here.
Also more curiously, you've rated the 'measures' lower than every other aspect of the product (I guess it looks like an 8/10), which I found dumbfounding.
If such a product, with such a high asking price for what it does could truly improve the USB audio chain, surely it would need to have a top ranking for it's 'measures'.


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