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!!!

Introduction
 
Everyone knows that the main purpose of any company is to sell as much as possible, in the most convenient manner, to the largest number of consumers. Therefore what does a product need to be successful? It should definitely be reliable, with high performance, at the best price and with an appealing aesthetic. Features in short, that are not only valid for any commercial proposal, but in particular for those that are part of the audio universe, whether consumer or professional.However, this world in particular can often lead us on to rough terrain, where supporters on one side or the other will always look at each other with distrust and suspicion deeming the views of the other party unreliable. Nevertheless, sometimes, however, there can be points of contact that can create an agreement between both audiophiles and audio professionals. We refer in particular to a product that created a bridge between both sectors, a headphone, or rather THE headphone against which all others must be measured and compared to. In short, we are talking about the Sennheiser HD 800 that for almost ten years has been the flagship of the German company, a model that has brought a real revolution in the universe of dynamic headphones and adopted by a large number of people, both for professional purposes and for pure entertainment. Around it were spent dozens of words, articles and reviews, with a commercial success that perhaps even Sennheiser never expected considering the quite challenging price of their flagship. But you know, progress moves faster, the market evolves and also the needs of customers. In this regard, we can safely say that, despite the high performance of the HD 800, it has always been a headset that only really unleashes its full potential if placed in certain conditions. According to our direct personal experience, the Sennheiser top of the range, may prove to a normal user, a tough headset to be correctly driven.At first glance in fact, the all too clear tone and some bass lightness, may turn up the noses of more than one user particularly when used with inadequate reproductive tools or connected to the headphone output of a normal iPod or DAP. This common problem has caused several manufacturers, including the same Sennheiser, to fill up the market with: dedicated headphone amplifiers, both tube and solid state; aftermarket headphone cables with generous section to try to emphasize the bass response, to the point of heavy tuning deployed by some American users. This last sequence of events in particular has sparked in various consumer forums and otherwise, the most diverse troubling threads even involving some influential journalists in the industry and making comparative graphs of the frequency response that the HD 800 offers before and after the changes spring up like mushrooms. Besides that, we know that the serious audio professional prefers to base his work on his own experience and the real practical value of the product used without listening in the slightest to audiophiles’ opinions or the empirical results of DIY. However, given either the logic of the market, or the evolution of the competing technologies, the manufacturers’ marketing policies have become more easily influenced and the actual sonic validity for these changes, must surely have reached the ears of Sennheiser. Everything has evolved from constant complaints over the years by many users in regards to a 6 kHz annoying peak and a modest fullness of low frequencies that make the response of the headphone a little unbalanced and highlights its difficulty to be used for some musical genres that are neither classical or jazz music. To overcome all of this and because, you know, the customer is always right, given the strong success of the 50,000 units sold, Sennheiser wanted to update the HD 800 project and give life to a new top of the range headphone that can be considered as its natural evolution i.e. the HD 800 S the object of our test.
 
 
Design
 
Aesthetically, the new HD 800 S doesn’t differ much from the previous one. It’s just more easily recognizable thanks to the outside black colour of the pavilions and the headband where there is always written HD 800 together with the serial number. The package supplied with the headset has written HD 800 S in silver at the center. The luxurious black case contains, in addition to the headset, two cables, 2.5 meters in length made of silver plated copper with a diameter of 36 AWG. While one of these is terminated with the classic 6.3 mm jack, and the other one is terminated with a 4-pole XLR balanced male connector to be used with balanced amplifiers. The instruction manual completes the package. The headphone pads are upholstered in Alcantara, a superb suede fabric, which is quite hard but it is very comfortable and water resistant. The rest of the headphone frame is made with aerospace approved materials, which contributes to make the HD 800 S acoustically inert. Being a fully open dynamic headset, it’s not recommended for outdoor use or in very noisy enviroments. The new top of the line adopts 56 mm drivers as did the previous one but the differences are not just aesthetic or monetary.The Sennheiser technicians were actually pretty uncooperative in giving us information about the differences between the two models, but much of the work done on HD 800 S derived from the test and the technologies implemented on the in-ear headphones IE800 on which a structure has been applied to reduce resonance and obtain a more balanced frequency response. The HD 800 S is referred as having a frequency response from 4 to 51,000 Hz (-10 dB) while the HD 800 is 6 to 51,000 Hz. Both with a nominal impedance of 300 ohms and a sensitivity of 102 dB. This difference in frequency, although it seems a minor detail on paper, as we will see, it’s rather the expression of an update that has greatly benefitted the product in terms of pure performance. The update uses an Helmholtz resonator to dilute the peak on the 6 kHz and adds a second harmonic at the bottom in order to make the yield of these frequencies more substantial and convincing. In essence, it has been usefully used a resonator with an anti-resonance function. It’s well known that the Helmholtz resonators can be used to amplify or cancel particular frequencies and this is the purpose of the small cylindrical resonator that has been placed within each of the headset drivers. It may seem very simple and even trivial, but as we have heard during our test it proved to be a very effective solution. The changes that at first have been developed and applied in an amateurish way by more savvy users, have been refined and applied ad hoc by the Germans in-house Sennheiser technicians. All of this has helped to ensure that the new top of the line has a well-defined sound character and a different one from the previous model.
 
 
Listening Test
 
As with every serious test carried out in our studio we left the headset to burn-in for a full week before doing any critical listening. We also wanted to use, for a comparison on equal terms, the previous HD 800 just to give an account of the actual differences between the two models. In addition to the cables supplied with the headphones, we wanted to use a couple of our balanced cables specifically built with military standard materials and of course we included the complete fleet of the amplifiers in our possession: the Lake People G-100, the iFi Audio iCAN SE, the Audio-GD Master 9 and the QES Labs HPBA-2 S that was specially built for this headphone according to our specifications. The peculiarity of the HPBA-2 S lies in the fact that besides being a dual-mono balanced current-driven amplifier, it has an output impedance that exactly follows and matches that of the HD 800/HD 800 S. This allows the Sennheiser flagship to express its full potential and make the most mainly as linearity in the upper part of the sound spectrum and as a transient response at low frequencies. We used ,as source, our DAW connected via USB and via S/PDIF to the two DACs in our studio, the Tobby by Firestone Audio and Stereo 96 by Mytek. As audio players we used JRiver with Fidelizer and Process Lasso Pro. All power and signal cables are custom design. The music used for the test included different genres with different resolutions and bit-depths. Starting from matching the G-100 with the HD 800 S with its unbalanced stock cable, we immediately noticed a greater depth and density of low frequencies combined with a higher linearity of the high frequencies. The annoying peak on 6 khz seems to have disappeared. The soundstage, which was one of the strengths of the old HD 800, remained unchanged. When moving on to use the iCAN SE with the stock unbalanced cable, the listening becomes more interesting as the higher output power of this amplifier shines thanks to its greater precision and focus when compared to the G-100. Everything becomes more appealing, more natural and the low frequencies acquire greater depth.These first hours of listening make us therefore understand that HD 800 S is definitely a big step forward compared to the previous model, and if we were to define this new headphone we would frankly say that this is a plug and play product. The HD 800 S gives us the impression of being more easily controllable and less picky in combinations with different amplifiers than the previous HD 800. Although to be honest, we are not particularly impressed by the performance of the enclosed cables; wires which in our opinion have a section that is too thin and can’t get a proper sound for the headset to express its fullest potential especially in the lower part of the sound spectrum. Also, in the same way as all the high-impedance headphones by Sennheiser such as the HD 600, HD 650 and HD 800 also the HD 800 S benefits from being driven in balanced mode thereby acquiring body, speed and accuracy during the sound reproduction when connected to a balanced amplifier with appropriate cables. In this regard, the balanced cables in our possession have sections of 18 AWG and 21 AWG that allow the HD 800 S to be more efficent at bass frequencies. However, the best is yet to come : we went even further by connecting the headset to our balanced amplifer the Master 9 by Audio-GD. If before we had only been able to guess the reproductive capacity of the new top of the line, thanks to the balanced connection and the more reproductive refinement, we were able to make the solid step forward that the new project called HD 800 S aimed to achieve. The new headset can be finally used to listen to various musical genres. The rock and electronic music records were faced and reproduced without any fear and without that sense of inadequacy that had characterized the previous HD 800. The basses are all there as well as the speed in the transient response, while the playback lets you enjoy no sound coloration of the entire sound message from the source in particular.Of course we can’t say the same about the impact on the lower part of the sound spectrum that distinguishes a headset like the Audeze LCD-X but we can safely place this HD 800 S, performance wise, with the HE-6 HIFIMAN detecting a greater sense of balance in timbre response compared to the latter, together with a greater ease of use. We shouldn’t define this new top of the line as a domesticated version of the previous HD 800, but we believe it’s more easily usable both by the audiophile and the more demanding professional. Regarding the professional use, we have been able to verify in the field that, in the same way as the previous model, also this new HD 800 S can be perfectly used in audio mastering sessions or critical listening tests. Especially if coupled with the HPBA-2 S balanced amplifier which is produced by the Italian company QES Labs according to our precise specifications and that drives the headphones in current mode. On more than one occasion we have recommended to other worldwide audio professionals, the pairing between the Sennheiser flagship and this amplifier and had always received thanks for this valuable advice. Also we have often used this combo for the mastering of different records with satisfactory results. Now with this new HD 800 S the circle can be defined as complete as this headphone has kept all the positive aspects of the previous one while filling up the gaps left by the old one. So we still see the main strengths, i.e. transparency, speed, soundstage, sound of voices, acoustic instruments, reproductive realism, but also the ability to detect problems such as saturation, silbilants, excessive compression and dynamic unbalance of the sound spectrum. If with the old HD 800 you had to, albeit with some difficulty, somehow calibrate your ears on the low yield, now everything becomes more immediate, more simple, especially if you are struggling with a recorded tune that has problems in the lower part of the sound spectrum. The balanced current driving of the HPBA-2 S and the impedance output curve which follows exactly the one expressed by the headphone, gives the HD 800 S the full potential of making us not regret the old top of the line at all while allowing us to be more confident in the process of audio mastering or critical listening of a song. It’s, according to our point of view, an important number of factors that push all audio professionals in favour of it, especially those who are looking for a reference system for their headphones listening chain where the HD 800 S, plays the main role offering great satisfaction in the configuration we used.
 
Final Thoughts
 
We are convinced that this new HD 800 S constitutes the perfect point of contact between the audiophile and the professional audio world. It’s a headset that doesn’t want to invade the territory of the best ortho-dynamics, but it’s definitely a product that, if put in a position to unleash its potential, can safely say it all. Like all the best products marketed by Sennheiser, the HD 800 S has a wide scalability in terms of performance especially if combined with the right amplifer. As we have heard during the long listening test, it completely undermines the old HD 800 from its throne of Queen of dynamic headphones going on to fill most of the gaps that the previous model had demonstrated. If we had to resort to a slogan to classify this new top of the line by Sennheiser, besides the aforementioned plug’n’play, we could say that listening pleasure meets precision. Of course for the price at which it’s sold maybe we can’t define it as a headphone for every pocket even considering the fact that, however, to play properly, it requires a reproductive sound chain of a certain level in terms of quality and money to be built around it. But sometimes in life you have to dare without fear and we put ourselves in the position to highly recommend it to both audiophiles and the most demanding professionals. Well done Sennheiser!
 
 
Personal Opinion
 
To be honest after purchasing the Audeze LCD-X and the Audio-GD Master 9 I stopped using the HD 800 and HPBA-2. In fact, I was working with a sound system that fully satisfied my business needs. However after the circulation of the first articles over the net about the changes of the HD 800, and especially after the official marketing notification by Sennheiser of a revised version of their flagship, I wanted to re-use what I had set aside for a while . So I did upgrade my HPBA-2 amp to the S version, and as soon as I got hold of HD 800 S I had to change my mind, falling completely in love at first listen because this new top of the line is really able to improve the performance in so many ways. The placement of the instruments and the amplitude within the soundstage is very precise as well as the neutrality of the sound message. The HD 800 S/HPBA-2 S combo is mind blowing for the performance it provides and frankly I think it’s hard to do better at least with regard to the use of a solid state balanced dual-mono amplifier combined with this new HD 800 S. Even a test with a Woo Audio WA5, a heavily modified tube amplifier, offered a very engaging and exciting listening thus confirming the quality of the product. That’s why I consider the HD 800 S a remarkable headphone, the best dynamic headphones that are currently sold on the market. Sure it does not guarantee the material impact of a LCD-X, in the bottom part of the spectrum or the fluidity of the LCD-3F on medium frequencies, but is definitely part of my set of tools for audio mastering and critical listening sessions, combining the pleasure of listening with precision. Two concepts that fully describe the characteristics of the HD 800 S and finally create a point of contact between the professional and the audiophile world.

Here is my personal review of HPBA-2S fully implemented by Qes Labs.
But first I want to point out some things.

-I come from the world of professional audio.I don't consider myself an audiophile in the true sense.
I have always tried and continue to seek the maximum of transparency and neutrality coming off my sources.
I did audio mastering for some years so you can imagine what kind of approach i have toward the monitoring of a
source be it a record made finished, a mix to master or a high resolution audio file.I always look for the most
analytical analysis possible.

-In the years I've used various types of headphones and most different pro amps.
From the simple analog amplifier contained in the console, in the DAT recorder to the current amplifier
built by professional firms such as SPL and Lake People.
Headphone used are sony mdr 7509hd, Beyer DT 880 600 ohm, AKG 270 studio, AKG 271 Studio, AKG K701.

-If I came to the choice of HD600 headphones and i consider them my reference cans there are several reasons.
I know the HD600 is an audiophile headphone, but when I started to question through
email some of the most renowned mastering engineers a couple of them
answered that the Sennheiser HD600's might be the one that suits my needs
These 2 guys are named Steve Hoffman and Bob Katz.About Bob Katz
i can clearly say he's one of the best mastering engineer in the world.And he's considered a guru in his field.
He has written a book that many people (myself included) in the professional world consider the bible of professional
audio.He's always very kind with his advices and suggestions.He is a real fan of headphones.

-I am not paid or in any way affiliated with Qes Labs.Before making any statement
on a device i do very specific and deep tests.I never ever say something because i was told
or because I saw a picture on a forum.Before i made the purchase I had the chance to try the amp with my headphones
and my cable for about 6 hours.So I made a pretty clear picture of how the hpba-2 sounded and sounds.

-All coloring devices or a device that leaves its own sound signature does not satisfy my sound needs.
This is a professional device.Conceived for a fully balanced circuitry
and built with the aim of monitoring without any sound coloration.
the device is according to EEC and has 2 years warranty.

-This is a machine made just for headphones at medium-high impedance (from 300 ohms up)

-My source for the test is starting from my Lynx L22 card connected with aes ebu to my mastering grade
Stereo 96 Mytek dac.Mytek is a company well known in the pro audio world and their converters
are found in many mastering studios.The cables connecting the dac to the hpba-2 are 2 custom cables
made of an an alloy of silver, copper and gold cryo treated.All the connectors are Neutrik XLR.
Before buying these cables, I used professional vovox cables, Mogami and van den Hul.
The cable of the hd600 is made by of ALO Audio model SXC terminated with Furutech XLR connectors.

-My headphone volume is about 80-83 db.At this level of sound pressure
the response of the human ear is almost flat (according to the theorem Fletcher-Manson)

-Before buying this amp I was able to use a SPL Phonitor and a Lake People G100
my faithful amp for more than a year.Both are professional products.


That said here's my review:

As you got to see the HPBA-2 is constructed in a stylish, functional and above all strong.
As requested to my personal specifications all internal connections are pure silver.
The connectors are Neutrik gold.The main and only reason of my purchase was solely to be able to use
a fully balanced headphone system with the most neutral frequency response.
I've used various reference recordings, but the one i've used most
is the DVD audio version of "The Nightfly" by Donald Fagen.
The DVD contains a lossless track (MLP) in stereo 24-bit 48 kHz.
I really listened to this record a lot of times.I want to point out that this record was used (especially in its first version on CD)
by many audio engineers around the world to calibrate sound systems or just test the audio system of a recording studio.
It's a masterpiece and a reference recording in the pro audio world.


The stereo image is really remarkable.You can clearly distinguish the location of all instruments within the mix.
The image is almost trimensional with a clear separation between the front and back
of the source you are listening to.What impressed me more apart from the transparency and neutrality has been
the transients response.Especially on the kick drum and bass.In the higher dynamics moments they clearly alert you of their presence without being boomy.
Dynamics are really really strong and the response to transients is very clear and very very precise .Much faster than my previous amp the Lake People G100.
The advantage of the concept of constant current drive and balanced connection is something you really feel and listen.
To be honest I begin to feel the dynamic "limits" of my hd600.Transparency neutrality,clean sound and dynamics are the main charateristics of this piece of gear.
The sound spectrum comes across its width without particular preponderance for some portion of some frequencies.
The timbre is very neutral and very very balanced.Obviously excellent recordings sound excellent without any flaw.
The bad ones are mercilessly vested with all their flaws.I can clearly hear reverb tails, I clearly hear if there is a problem of phase shifting (reversed phase),
I feel perfectly as I had never happened before the pumping of the compressor in some records that weren't properly mastered or mixed.
I clearly hear click or wrong fades.
To summarize i can state that i have a very very precise picture of what comes from the source.

The hpba-2 fulfills my needs for monitoring the source without any sound coloration.Really a great product!


I think that this product is in the same ballpark as the b22.With the difference(according to a friend who is also a mastering engineer that has tried both amps and whose ears i trust a lot) that the hpba-2 is built and conceived to be a reference pro monitoring system.The b22 is really an excellent product but it belongs to the audiophile world.
I'm not here to say that one is better than the other.
I only want to say that my goal was to a have a pro balanced headphone system without any sound coloration.
That's why i bought the HPBA-2 mde by Qes Labs.

I hope you'll satisfied with all the curiosities about this wonderful device.


cheers