Intro
 
    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!
 
Disclaimer/Acknowledgement
 
    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. 
    
Packing
 
    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).
 
 
 
  
 
Features
- 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:
 

 
Build/Design
 
    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.
 
 
 
 
 

 
 
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.“
(http://www.PCGuide.com)
 
“ 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. “
(http://www.mojo-audio.com)
 
“ 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. “
(http://www.positive-feedback.com)
 
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!
 
Comparison
 
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.
 
Value
 
    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.
 
Conclusion
 
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!
    
 
 
 

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.

Introduction
 
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.
 
Design
 
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!!!

Part 1 - TORTURE TEST
 
So, have you ever heard the noise from an old laptop's hard drive spinning-up, or the electronic "chirp" of your mouse cursor moving across your screen during music playback??  Chances are that if you're using a half-way decent PC/MAC from last 10 years or so, that you haven't.  But hey, I figured why not REALLY test what this device can do?  Where's the challenge in cleaning-up already clean, modern USB 3.0 connections?  (SPOILER!  By the way, it made my modern USB 2.0 & 3.0 signals sound incredibly clear.)  So the performance torture test was devised.  I grabbed our old HP and DELL  laptops from the basement Pentium (Yes, PLAIN INTEL single core PENTIUM CPUs) PC archives (Read as spare parts rack) and coaxed them back to life running old versions of Windows XP & using Windows media player or FOOBAR 2000 and played old 16-bit sampled mp3 files.  Did it magically make this old equipment and poorly sampled, high-loss audio files sound like high-end audiophile-worthy output?  NO.  But what it DID do to my surprise is reduce the harsh, "ringing" (The only way I can describe the distortion/aliasing from the mp3 files) and virtually eliminated the noise from the poorly-shielded components in both laptops.  No screeches or squawks randomly intruding on the playback once the iPurifier 2 was in the audio chain.  Unfortunately, DSD files were a bit too much for these old laptops, but they DID manage to do justice with some of my lower-sampled FLAC files, and actually managed to make them sound GOOD!  (CPU run-time was maxxed-out, and nothing else could be done on the PC at the same time while the files were playing back though.)  All in all, a VERY impressive result.  
 
Part 2 - THE ACTUAL REVIEW
 
I evaluated the iFi iPurifier 2 with the following equipment:
SOURCE - Dell XPS 8500, Dell Inspiron 530 (Both running Windows 10 PRO 64-bit)
DAC - iFi iDSD (DAC) FIIO e17 (DAC) ONKYO TX-NR636 (DAC) iBASSO DX90 (DAC)
AMP - iFi iDSD, iFi iCAN, iFi iCAN SE, Schiit Audio ASGARD 2, & ONKYO TX-NR636
HeadPhones - Beyerdynamic T1 (ver.2), HifiMan HE400i, Sennheiser HD-650, HD-800
Player Suite - Foobar 2000, & JRiver Mediacenter 21
 
Now I'm not going to throw a bunch of specs at you as they are all over the web and in other reviews, so I will keep this to "what I experienced personally":
 
When I listen to music over my DLNA server, I am just listening passively.  When I go directly from my media PCs using FOOBAR or MediaCenter 21, I am usually actively listening, and looking to lose myself in the audio.  The iPurifier 2 is best enjoyed by me during the latter setting.  To be honest, my configuration already sounded pretty good to me as it was.  I never was wanting for clearer signal, or more refined detail.  I knew it was out there, but I figured that the pursuit of it would be so cost-prohibitive, that it really wasn't something that I couldn't live without.  (Incorrect assumption #1)
 
So when I was sent the iPurifier 2 to try out with my audio gear, I was kind of skeptical to be honest.  I mean, USB filtering?  How much of a difference can THAT make? (Incorrect assumption #2)  
 
First, this piece of kit does a good shade more than "just filter";  It re-clocks, conditions, boosts, & noise cancels.  All seamlessly, with NO drivers or configurations needed.  It is literally "plug-n-play", and how often does something THAT simple happen nowadays?
 
So what did I hear?  

1. In my mp3 low-res files, it softened the "edge" of some of my harsher low-quality 16-bit recordings. (Think old Bruce Springsteen and George Thorogood live performances that sound almost 8-bit...  But are SO fun to listen to!)
2. In my basic 14.4 FLAC files, it brought-out more of the layers in instrumentals.  (There are sub-riffs in Pink Floyds' "Learning To Fly" & "Money" that I never heard quite so prominently. before.) 
3. In my Hi-res FLAC rips from CD there was just more "oomf" and weight to song from The Moody Blues, Alan Parson Project (YOU MUST hear "La Sagrada Familia" with the iPurifier 2 enhancing!)
4. In my DSD 2.8MHz & 5.6MHz files the improvements were bother more difficult to catch, yet more impactful at the same time.  There was less to correct, but what WAS corrected just stood out all the more. Holst, Wagner, Clapton, Michael Jackson, Billy Joel, Toshiro Masuda, Kitaro, it all just took me 10s of hours to get past trying to listen the subtle nuances that I had never heard before and truly enjoy!

 
So what's the point?
 
For me, the iPurifier 2 represents if nothing else, the single SIMPLEST way to enhance all of your audio collection in one fell swoop.  Will it be as dramatic an upgrade as upgrading from a sub-$100 "generic" DAC to a higher-end iDSD Micro, Chord Hugo/Mojo or better?  Probably not.  But there is simply no other addition to your audio chain that you can simply "plug-in", and not even have to power it on, that will have as much impact on your audio as the iPurifier 2 that I have ever heard of.

I am a member of the ifi iClub and a couple of months ago ifi Audio offered some of there newly released products for review. I already own the ifi micro iDSD so I decided to see if the new iPurifier2 could further enhance the sound of the iDSD.  I also asked ifi to supply a Mercury USB cable. The items where shipped very quickly by Select Audio.
 
Equipment used for testing:
 

1. ifi micro iDSD
2. ifi micro iDAC 2
3. Mercury USB cable
4. Beyerdynamic T1 Headphone
5. Beyerdynamic A20 headphone amp
6. Sennheiser IE80 Headphone
7. Geek Out IEM 100 Dac/headphone amp

 
The iPurifier is shipped in a sturdy box with an additional USB-A adapter. The review sample i received had the Type B USB connector, which should be a good fit for most DACs out there. The build quality of the device is excellent and in all settings the device was always recognized by the computer and did work without any dropouts or disruptions.
 

 
 
 
 
I primarily tested the iPurifier2 with the headphones mentioned above but also on my main system. In whatever setting I used the iPurifer 2 there was a sense of music starting the flow more natural and it sounded more “analog” to me. The digital strain sometimes associated with digital music was less so. Complex musical details like at the beginning of the first track of the Miles Davis album “Sketches of Spain”, “Concerto de Aranjuez: Adagio” (PCM, 24bit, 88.2khz), were easy to listen to.  With every track I tried from Kraftwerk to classical music there was a veil lifted. My overall listening experience became more relaxed and enjoyable.  The soundstage has improved and instrument separation is clearer.
 
I started the test using my micro iDSD. The iDSD already has the previous iPurifier built in but still benefited from the extra features of the new iPurifier. The only caveat with the iDSD is that the iPurifier wont fit straight into the iDSD USB port (when RCA cables are used).  My iPurifier2 came with a USB-B female connector but even with the USB-A Male plug the device wont be a straight fit due to its size.
 

 
 
During the review I purchased the new ifi iDAC2. The combination of the iDAC2 with the iPurifier2 is a match made in heaven. The iPurifier plugs straight in and the sound is even warmer and more analog than with the iDSD. The combination of the new iDAC with iPurifier2 has now replaced my iDSD in my main system. The iPurifier2 is one of these products that you put into your system and then forget about them until you take it away and then realize you cant live without it anymore.
 
It does what it says on the tin, the USB signal is improved by providing a cleaner USB signal with much less digital artifacts and noise. If you enjoy the musical flow and naturalness of analog sound you will enjoy the iPurifier2. Highly recommended.
 
I have purchased the review sample. 

Acknowledgment

The iPurifier2 was loaned to me along with the Micro iDAC2 by iFi for the purpose of this review, and I previously won an iFi Micro iUSB3.0 in the launch contest for the iUSB3.0. The opinions in this review are my honest opinions.

Introduction

Last year I won the iUSB3.0 in its launch contest. I have had the iUSB3.0 for about 6 months and have used it with several DACs: LH Labs Geek Out 1000, LH Labs Geek Out V2, Schiit Yggdrasil, LH Labs Geek Pulse X-Infinity, and the iFi Micro iDAC2. My observations in my iUSB3.0 review were that the iUSB3.0 had several effects: the noise floor is substantially lowered; instrument separation is increased; soundstage depth, width and height are increased; and the decay of notes is fuller and more natural. On reflection, I think most of these elements are related to the first element, lowering the noise floor. The Micro iUSB3.0 is a fantastic bit of kit, and I’m very glad to have won it, but when I’m traveling, it isn’t terribly portable. It needs two USB cables and a power socket to run, which adds up to a lot of gear to carry around. It also costs a pretty penny at around $400 (£329 when I won it). The honest folks at iFi say that you shouldn’t get an iUSB3.0 to use with a DAC that is less than $5000,and they are probably being sensible on that.
 
Quote in the Nano iUSB3.0 launch thread (post 5):
“If your USB DAC is:
1) USB dac <US$500 eg nano DSD = iPurifier 2 (ie. no need for mUSB3.0 or nUSB3.0).
2) USB dac US$500 to US$5k eg iFi/Chord = nano USB3.0.
3) USB dac >US$5k eg DCS/AMR = micro iUSB3.0.
 
Hopefully this summary shows that if you have a <US$1k DAC, then the micro iUSB3.0 is overkill as unlikely to hear the additional performance.”
 
I’ve used the iUSB3.0 with lesser DACs to good effect, but I didn’t pay for mine.  I also use two double ended USB cables that I got at big discounts through the LH Labs Geek Pulse IndieGoGo campaign (the campaign that less people are threatening to burn LH Labs down over).
 
The iPurifier2 has most of the technology in the Micro iUSB3.0, but is about ¼ the price and at most requires one USB cable and an adapter. The iPurifier2 comes in three varieties, all with USB3.0 female ends to insert a USB cable jack, but with different outputs: USB-A (female) for hooking up to the iFi Micro iDSD or a stick DAC like the Audioquest Dragonfly or Geek Out V2, USB-B for hooking up to most full-size DACs, USB-C for next generation devices, and USB-micro for many portable devices out there. The unit I received was the USB-B unit, which included USB-B (male) to USB-A (female) adaptor. The adaptor was appreciated as it allows wide usage. I was able to use the device with every DAC or DAP I own (most of us own a USB-micro cable for charging some electronic device).
 
Every person walking around this earth is biased, and I’m no different, so I’ve included a blurb about my particular flavour of bias below the spoiler. Read it if you want to.
 
 

Form & Function

The iPurifier2 is tiny and comes in a tiny box not much bigger than a pack of cards. The box includes a warranty card, instructions, the iPurifier2, and in the case of the iPurifier2 USB-B version, a USB-B (male) to USB-A (female) adaptor.  It will fit in a change pocket or small purse, but you’ll still need a USB cable. If you are carrying around a DAC, you’ve probably got room for the iPurifier2.
 
 
 
The iPurifier2 has two LEDs. When the device is receiving power but not plugged into a DAC both lights are blue. Plug the iPurifier2 into a DAC and the left light turns green.
 
According to the iFi website:


Comparatively, the Micro iUSB3.0 has the following features (video from product launch), stats from iFi website:


 

The Micro iUSB3.0 is much larger. You’ll need two cables and you’ll probably want a case to carry it around. It has Micro in the name, but it is really inconvenient to move, especially when you consider that you will be carrying around the iPower and probably will be using two USB cables. I use the Micro iUSB3.0 plugged into my LH Labs Geek Pulse X-Infinity, which is a spectacular DAC and pre-amp with a middle of the road headphone amp, hooked up with two split power and data LH Labs Lightspeed 2g cables (I got the pair for <$250).
 

Technical testing

The equipment used for technical testing was as follows:

1. Wensa SPL Meter
2. iFi Micro iDAC2
3. iFi Micro iUSB3.0
4. iFi iPurifier2
5. 2 LH Labs Lightspeed 2G cables
6. Meze Audio 99 Classics Headphones
7.  

When I initially listened to my DACs fed through the iUSB3.0 I noticed that my music sounded louder. As many are aware, louder music generally sounds better to our perception, so a device that increases volume will be perceived to increase sound quality and bias our judgment. At the time I won the Micro iUSB3.0, I didn’t have a SPL meter, but this has since been remedied. I decided that the first test I would run in this review was to see if there were any differences in SPL measurements with the iDAC2 at the same volume between the iDAC2 alone, iDAC2 with iPurifier2 and iDAC2 with Micro iUSB3.0.
 
The test procedure involved the following steps:

• Set volume level using white noise (Ayre Acoustics – Irrational But Efficacious System Enhancement Disc) to approximately 75 dB using SPL meter set to A weighting and slow response with iDAC2 as the source. This is to establish baseline.
• For each of iDAC2, iDAC2 with iPurifier2, and iDAC2 with Micro iUSB3.0 repeat seven times
  • Turn on SPL meter
  • Set to slow and A weighting
  • Angle foam capped condenser microphone into Meze Audio 99 Classics left earcup
  • Begin white noise track and let play for three seconds
  • Begin one minute timer
  • Record minimum and maximum decibel measurement (range) during one minute interval
  • Estimate median SPL measurement
  • Turn off SPL meter

 
I did not use clamps to maintain fixed position of the headphone or SPL meter. All measurements were done by hand, which introduces additional potential for measurement error. The results of the testing are in the table below.
 
 
Given the table results above, it does not appear that there are any measurable differences between the iDAC2 alone and with USB devices. The small sample size caveat applies, but it is also the case that given the measurement error in hand measurement that further trials would have likely yielded little or no additional information. These results can be interpreted to mean that any perceived volume differences are due to elimination of noise on the signal, which is a tangible benefit to audio quality.
 
After I had already run this experiment, I was informed by iFi that it isn’t possible from an engineering perspective for the iPurifier2 or Micro iUSB3.0 to make the sound physically louder. This little experiment is a good example of why you can’t always trust your brain, while at the same time being an example of why you should trust your ears. That perceived louder sound is really about lowering the noise floor and creating a blacker background. It makes your music more dynamic, which is also what happens when you increase the volume. The brain doesn’t always make the right diagnosis of what the ears are hearing.
 

Audio quality

I used the iPurifier2 primarily with the iDAC2, but also got some listening time with my LH Labs gear (X-Infinity, Geek Out V2, and Geek Out 1000). The iPurifier2 and iDAC2 have been my constant companions for nearly a month. They are good company and work well together, but of the two, I prefer the iPurifier2. The iDAC2 is supposed to be the hero, Batman to the iPurifier2’s Robin, but I like the sidekick. The iPurifier2 probably won’t be killed through any sort of supervillainy either, it feels substantial in its tiny aluminum package. I tested the iPurifier2 with my LH Labs Lightspeed 2G cables and with the USB3.0 cable that came with the Micro iUSB3.0. I listened to many different tracks, and many different styles of music. I listened through speakers and through headphones The iPurifier2 performs similar feats with all of them.
 
What I hear when I listen with the iPurifier2 is a blacker background, which lends to better instrument separation. Instruments have a more ‘suspended in space’ quality to them. Bass is fuller and drums have noticeably more kick. Notes have a more natural feel to them, a pleasant roundness. When listening to Kraftwerk – Kometenmelodie2 via the iDAC2 there was a slight smear to treble detail without the iPurifier2, adding it to the chain improved timing and made the treble more detailed. When listening to Mavis Staples – If It’s A Light I notice backing vocals more distinctly with the iPurifier2. The lead vocal has more definition and the bass is tighter and groovier. On Teddy Thompson’s cover of Leonard Cohen’s brilliant Tonight Will Be Fine, I hear the vocals just a hair cleaner and instrument spacing improved in the better blacker background. Others have proclaimed miracles about the expansion of sound stage. The iPurifier2 will not be keeping a drunken party going like a tiny British Jesus, but it will add some power to the cocktails already there. I didn’t hear miracles. I did hear improvement in depth, a little improvement in width and no discernible difference in height with the iPurifier2. The headphones I listened with were the Meze Audio 99 Classics (which I had on loan from Meze Audio), and my panty-hose modded Sennheiser HD600 (mod increases treble definition, removes some veil and improves soundstage, try it), and a variety of IEMs (Trinity Audio Atlas, 64Audio X2, Echobox Audio Finder X1). It may be that bigger differences in improvement on soundstage are had with higher end headphones, but I didn’t have any of those on hand, so I can only report my observations with what I have. The iPurifier2 made a nice difference when I listened with the generic USB3.0 cable supplied with the iUSB3.0, but when I upgraded cables to LH Labs Lightspeed 2G, I didn’t hear as much uptick in performance as I did with the Micro iUSB3.0.
 
The iUSB3.0 expands width a bit more and depth plainly more than the iPurifier2, but also gives a boost to height. When listening to Kraftwerk – Autobahn through 28 year old Mordaunt Short speakers I got for £20 off ebay,  the X-Infinity, and the Cambridge Audio Azur 540A the soundstage is as tall as my living room. It is spectacular. I didn’t get the same improvement with the iPurifier2. The iUSB3.0 also responds to higher end USB cables in a way that the iPurifier2 doesn’t. When I got the iUSB3.0, I had a Supra USB running between the computer and the Micro iUSB3.0 and a Lightspeed 2G cable to my Geek Out V2, replacing the Supra cable with the LH Labs Lightspeed 2G improved the treble definition. Switching between the cables on the iPurifier2 didn’t seem to have an effect. Hooking my portable hard-drive into the Micro iUSB3.0 also improved my sound a smidgeon. The sound was a little cleaner, more organic. Differences in sound stage were relatively easy to hear on the iUSB3.0 vs. the iPurifier2, but the change that I think most people will notice is the increased richness in the bass. The bass is fuller and richer on the iUSB3.0, it is a joy.
 

Conclusions

I’m a fan of the iPurifier2, but I’ve been spoiled on the much more expensive and more performance laden Micro iUSB3.0. Since my loan period began on the iPurifier2, the Nano iUSB3.0 has been released, bringing  much of the features of the Micro iUSB3.0 at half the price. I think that this is a good strategy for iFi, as all of these technologies work, but using the Micro iUSB3.0 with an inexpensive DAC is definitely overkill, albeit beautiful sounding overkill. I think iFi’s bracketing of prices has as much to do with the gear they expect people to be listening with as the price of the DAC that the iPurifier or iUSB3.0 device is feeding. Whatever your budget, iFi now has a device at a reasonable price to improve your USB DAC’s sound quality.
 
I think that the iPurifier2 is a great value. At $110 it is better value than basically any audio device you can buy in that range. It provides definite improvement in soundstage depth, lays down some tight and groovy bass, and improves note definition by improving the blackness of the background and preventing time smearing (as noted in Kometenmelodie2). I give these a solid 4 stars. They are extremely portable, work universally, and give marked improvements in audio quality

If you are reading this, you are more than likely interested in squeezing out the last drop of quality from your gear.  That can mean cable replacements, power conditioning, silver fuses, silver plugs, the list goes on.  Most of those can end up costing a lot for those small gains. The iPurifier 2, although still an investment, is a new option from iFi to help persuade your gear to sound better.
 
So what does it do?
 
If you read the blub on the iFi site it contains lots of info which I'm not going to repeat here. Suffice to say the iPurifier 2 takes a noisy USB signal destined for a USB DAC and cleans it up! the end result should be better audio quality reaching your ears. 
 
Without further ado, here's some pics:
 

 

 

 

 
 
Does it work?
 
I have to say for me, yes.
 
I have a Schiit stack connected to my PC, a Modi DAC and Magni class AB amp.  I play Hi-Res tracks quite happily through my HE-500 phones.  I figured this would be as good a test as anything for the iPurifier 2.
 
The device itself is very robust and well engineered. As you can see from the photos it's fairly discrete. There are a couple of indicator lights for Power and Sound signal. The device also comes with a range of connector options.  I have the USB-B but it comes in A, C and Micro B also.
 
I've got to say, I really wasn't expecting much, if any improvement in the audio quality from my Schiit stack as it is a fairly silent and quite revealing setup. 
 
For my test I fired up one of my most familiar and favourite test albums, Rumours by Fleetwood Mac (in 24/96 from HD Tracks - the max the Modi can handle) and listened to the first few tracks a few times.
 
I then added the iPurifier to the chain.  Again, I listened to the first few tracks.  At first I didn't really notice too much of a difference, until I got to the second track, Dreams.  The splash cymbal at the beginning caught me by surprise a little, it seemed more sustained and cleaner than I remembered.  I looped this part of the track a few times, removed the iPurifier and repeated.  Sure enough, I can tell the difference pretty easily.  After a few hours of listening with the ipurifier attached, I've decided it's staying put in this setup.  To my ears it makes a good difference to the general soundstage (width especially) and overall clarity of the sound. I like it!
 
Makes me wonder about adding the iFi iUSB Power to the mix if this little thing can make a decenet improvement, who knows what that will do......sorry wallet.

I was lucky enough to get an iP2 on loan from ifi audio last week and have been trying it out with my laptop based iDSD system for a few days now. So I have the micro iDSD coupled to the first gen iUSB power with Gemini cables and a Mercury cable from laptop to iDSD. Oh yes and a pair of HD700s to top it all off.
 
So I have been burning up Tidal all week and had a listen through a small selection of my favourite albums with and without the iP2 and then also comparing it with the Audioquest Jitterbug (which is mine!)

Aretha, Chain of fools
James Bay, Chaos & the calm
Dusty, In Memphis
Eagles, Hotel California
Keb Mo', Keb Mo'
Leon Bridges, Coming Home
Lou, Transformer
Rickie Lee Jones, RLJ
T.Rex, Electric warrior

So trying for a fairly broad mixture.
The differences are not massive but are significant and important in respect of my preferences
The bass feels tighter and more textured but I cant be sure if it is more extended........but that doesn't matter as it sounds better!
The treble is clearer and less splashy
The mids are clearer.
The soundstage is better resolved with more space around instruments and vocalists. It feels like it is better layered in width and depth, much as when you change from HD700s to HD800s. Or single ended cables to balanced. Or regular vinyl to half speed mastered MoFi Vinyl. So not "Do you see the light" different but significant and positive different. It is also a better improvement that the Jitterbug which is an improvement too, but not as complete or significant as the iP2.
 
The most telling thing I can say is that it is very difficult not to just get wrapped up in the music now and not be listening for specific details.

Overall I'd say its more value than balanced cables were for my HD800s and I thought that was worthwhile and I will be ordering one for my system as soon as the USB A version is available and then I can ditch that adapter thing.


Hope this is of interest? This is my first ever review so any constructive feedback would be helpful to me!