A WORLD PREMIERE

his will be a long text. Very long to be honest. Pro iDSD is a unique device both for its manufacturer, iFi AUDIO, and for the market. iFi Audio is a part of the ABBINGDON GLOBAL GROUP, the owner of the high-end brand called Abbingdon Music Research (AMR). It's primarily about the consumer market (hi-fi), but also - and iFi is actually interested in it - a professional (pro) one. The volume of the text results from the extraordinary versatility of the tested device. We have been meeting this phenomenon for some time and everything indicates that it will intensify: digital devices now combine several functions. Although almost always one of them is the primary one, each of them must be described and tested separately; normally it would be in a few separate tests.

iFi Audio is a company known for its small, often tiny devices, mainly digital-to-analogue converters, headphone amplifiers, phono preamplifiers, etc. I think two years ago, if I remember correctly, it presented a device that – keeping in mind its earlier products - could be called a "full-size" one - the Pro iCAN headphone amplifier.

It offered a classic headphone jack, ø 6.3 mm output, but it was a symmetrical design and featured also balanced outputs. It was important that the amplifier was intended not only for home use, but could also be part of the recording studio equipment. Which makes sense, because due to the boom of inexpensive digital recording and editing systems, virtually anyone can have a ministudio at home. "Pro" before "iCan" was therefore an important addition.

| PRO iDSD

Featuring a very similar chassis, which is of a half-width of a studio rack, the Pro iDSD was supposed to hit the market in the first quarter of 2017, eventually its premiere took place on January 15, 2018. The reason for the delay seems trivial - last year a lot of products appeared on the market with a higher specification, mainly regarding DSD signal playback and conversion of PCM signal to DSD than before, and iFi had to adjust to these changes.

Equally important, perhaps even more important, was the explosion, because it can not be called otherwise, of the MQA (Master Quality Authenticated). We wrote about it on the occasion of testing Mycek DACs, so there is no need to repeat everything. Pro iDSD has a built-in MQA decoder, and can act as a file player, read from both the NAS and the internet, as well as from the local USB memory. So it would be another, after the Mojo / Poly Chord Electronics system, case of extending the functionality of a D/A converter with the function of a file player ("renderer").

Digital-to-Analogue Converter

Despite this impressive functionality, the company materials leave no doubt as to the main function of this device - it's a digital-to-analogue converter:

Pro iDSD is a reference digital-to-analog "state of the art" converter. It will be great to use in many situations - as a wireless file player or main DAC in an expensive, high-end home system, to name just two possibilities. The built-in headphone amplifier section means you can connect high-end headphones to it.

iFi Pro iDSD, manual, p. 1

These few sentences explain a lot of possibilities that the tested DAC offers to its user. As a D/A converter it offers following digital inputs: BNC (S/PDIF), RCA (S/PDIF), XLR (AES/EBU) and USB 3.0. The BNC input can be configured in several ways, because in addition to accepting a digital music signal it can act as an input for an external word clock and as an input synchronizing several converters in a multi-channel system, which would be similar to what Mytek offers in their Brooklyn DAC+, also focused on both the consumer and the pro market.

Pro iDSD is an advanced digital product, which is indicated by its technical specification but becomes obviouse once you read about the solutions used in it. One of them is a modern chip working in the USB input. Manufacturer chose the XMOS XU216 X-Core 200 DSP for this job, enabling transmission of PCM signal up to 32 bits and 768 kHz as well as DSD up to DSD512 (!). Its second function is to work as a file player that accepts and decodes audio files with a PCM signal up to 32 bits and 192 kHz and DSD (DoP).

Such impressive parameters were possible to achieve, because while the standard Burr-Brown DAC chips were used, but in a self-developed configuration - there are four stereo chips with a differential output, allowing to decode the PCM signal up to 2 x DXD, or 768 kHz, as well DSD signal up to DSD1024. This last value is not a triumph of form over content at all! .

A separate DSP chip has been used to operate digital filters. Usually manufacturer use filters implemented in DAC chips, this is not a bad option. However, if we are persuing the highest sound quality, we have to resort to a different solution, that is, to design our own digital filter, implemented in a DSP. By expanding the range of what iFi Audio converter can do, iFi went even further.

Pro iDSD offers three basic operating modes: "Direct", "PCM - Upsampling" and "DSD - Upsampling". In the first signal is processed without changes, not even oversampling is performed (i.e. increasing the sampling frequency), which is similar to the operation of the legendary DAC chip, Philips TDA 1543. For DSD signal it means that it is converted into analog one without any digital processing. The next two modes include upsampling of any signal either to PCM 705,6/768 kHz, so sixteen times higher than the sampling rate of a CD/DAT tape, or convert it into a DSD signal: DSD512 or DSD1024.

As I mentioned in the review of the Ayon Audio CD-35 High Fidelity Edition, and also when reviewing the Audiophile Speaker Set-up 2 x HD release, the higher sampling frequencies of DSD signal translate into much lower noise in the audible band, and thus better sound. The Japanese got into it all and started to offer DSD256 albums (DSD-DSF 11.29696 MHz) on BD-ROMs. Upsampling in iFi is to perform a similar function, i.e. to help D/Converters to do their job in a better way.

However, this is just the beginning. If we choose the upsampling mode, we can also choose the type of a digital filter. In addition to the Bitperfect mode, i.e. without any filter, we can choose from: Bitperfect +, Minimum Phase, Apodising and Transient Aligned ones. Without going into details, let's just say that Bitperfect + only corrects frequency responce cutoff, Minimum Phase eliminates oscillations before the impulse, Apodising - invented and propagated by Meridian - has no oscillation before or after the impulse, and Transient Aligned is a classic filter with steep descent of the frequency response beyond half the sampling frequency.

User can also choose a mode analogue output works in:

| ‘Solid-State' – based on J-FETs, operating in A Class,
| 'Tube' – based on NOS GE5670W double triodes ,
| 'Tube+' – same tube circuit but with a minimum feedback.

Audio files player / renderer

This will be an increasingly common scenario, because the integration of digital products is becoming cheaper, and therefore more common: with the D/A converter we get also an audio file player. It is not an equally sophisticated device as free-standing Linn , Lumïn, Aurender, or dCS products, but good enough to be used, for example, to listen to Tidal streaming or to occasionally listening to files from a NAS drive. On the functional side, however, it is a full-fledged product that will play files from sources compatible with the DLNA protocol, and decode the MQA files. The signal can come from the internet, a NAS drive, a local hard drive or a USB stick, as well as from a SDHC card.

During the test, the company did not offer its own control application, recommending the use of the free MUZO program. I wanted to use also Linn Kinsky software but it was not possible because each time I sterted playback the sound froze after a few seconds, and I was unable to solve this problem. Perhaps the fault lies on the side of my home network, but without a dedicated player it was hard to say

Headphone amplifier

As it reads in company materials, the main difference between Pro iCAN and Pro iDSD is double the output of the former, and the fact that its output section is always working in Class A. The headphone amplifier in Pro iDSD is optimized as a line section – it's simple a section of the stage of the D/A converter with a volume control. The output it can offer is therefore smaller and most of the time the output section works in the Class AB.

iFi Audio Pro iRack

With the launch of the Pro iDSD DAC, the iFi Audio decided to launch iRack, dedicated to the Pro series. With its naming, it refers to the iRack cabinet, produced for several years, whose task was to hold a system composed of several iFi micro components in an orderly fashion.

The basis for this framework structure are four large rolls made of marble. At the top and bottom of each of them, there are aluminum cones, finished with rubber absorbers. The whole is connected by thin profiles made of aluminum-magnesium alloy, which meet in a centrally located disc made of duralumin alloy. The Pro series devices are placed freely on additional absorbers, mounted on the profiles connecting the entire structure.

Price (in Poland): 1399 PLN for one rack

As I said, it's a versatile device, that's why the number of combinations is huge. I will only say that the Ayon Audio CD-35 HF Edition transport section, the Lumïn T1 file player and the PC computer worked as the digital signal sources. I used HiFiMAN HE-1000 V2 and Edition X V2 headphones to evaluate the headphone amplifier. The DAC was connected to the "High Fidelity" reference system using the Acoustic Revive RCA-1.0 Absolute interconnect. As references, I used Ayon Audio HE-3 and Octave V 16 headphone amplifiers.

More important, as it seems to me, were the choices I made during the auditions, regarding upsampling, filters and the output mode. You can choose any scenario suitable for you, however, I would suggest to start from two options: 'Bitperfect' + 'Tube +' or 'PCM Upsampling' + 'Apodising' + 'Tube +'. The former is absolutely unique in how it reaches the inside of the sound, how it differentiates it. In turn, the latter is smoother, richer, resembling the sound of a turntable.

I was not convinced by the performance of the DSD upsampling, because it seemed to add artifacts to the sound, i.e. colored it. Part of the lower midrange and upper bass was emphasized with it, and the upper midrange was rolled off. It also lacked resolution, that was so exceptional without upsampling. But maybe in your system it will be THE one and only setting – you should find that out. If you need an absolutely direct sound, as fast as possible, try the solid-state output as well.

Recordings used for the test (a selec- tion

|Compact Disc

• Andrzej Kurylewicz Quintet, Go Right, Polskie Nagrania „Muza”/Warner Music Poland 4648809, „Polish Jazz | vol. 0”, Master CD-R (1963/2016);
• Ariel Ramirez, Misa Criolla, José Carreras, Philips/Lasting Impression Music LIM K2HD 040, K2HD Mastering, „24 Gold Direct-from-Master Edition UDM”, Master CD-R (1964/2009).
• Bogdan Hołownia, Chwile, Sony Music Polska 5052882, „Pre-master”, Master CD-R (2001)
• R-men, I thought about you, T-TOC Records MCDR 3002, „Platinum Gold Sound”, Master CD-RIIα (2010)

|Pliki hi-res

• 2xHD. DSD, USB Flash, DSD64/DSD128
• FIM Super Sound! I, First Impression Music FIM DXD 066 USB, Promo USB Flash, FLAC 24/176
• Various, Polish Jazz | Remaster 2016, Master WAV 24/88,2
• Anne Bisson, Blue Mind, Camilio Records CAMUSB141, USB Flash, FLAC 24/96 (2009)
• Eric Bibb, A Selection of analogue Eric Bibb, Opus3, DSD128
• Leonard Cohen, Popular Problems, Sony Music Labels SICP-4329/HDTracks, WAV 24/96 (2014)

|Tidal

• Jackson Browne, Late For The Sky, Asylum Records INR 04191/Tidal, MQA Studio 24/192 (1974/2015)
• Kuba Badach, Oldschool, Agora/Tidal, FLAC 16/44,1 (2017)
• Kuba Więcek Trio, Another Raindrop, Polskie Nagrania „Muza”/Tidal, FLAC 16/44,1, Polish Jazz vol. 78 (2017)
• Kurt Elling, Passion World, Digital Distribution Serbia/Tidal, MQA Studio 24/96 (2015)
• Urbanator Days, Beats & Pieces, Agora/Tidal, FLAC 16/44,1 (2018)

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Japanese issues available at

| D/A Converter

This is a unique device! Even when we forget about its functionality, including the ability to adjust the sound to your own taste and system, even if it was just a DAC, it would still be good enough to recommend it even for expensive high-end systems. No, it will not offer everything that such systems can, lets keep it real. In many cases, however, it will not matter. The way in which it conveys the sound, its basis, i.e. something on which everything else is built, belongs to the high-end without any "buts" and other qualifiers.

What stroke me first was how detailed the sound was, how rich with information. I heard it with CDs - Master CD-Rs to be exact, but still limited to 16 bits and 44.1 kHz - and with high resolution files played from a computer. It is a formally rich sound - formally, that is at the base, inside. My point is that everything that iFi presents is built around a dense "core." And this is a saturation with harmonics. I do not know any other reason for this kind sound, but this could be also explained by a low jitter.

Since the basic input of this device is USB, I spent most of my time listening to music from hi-res files. The DAC perfectly differentiates them, i.e. shows what DSD signal has to offer and what PCM has. In this case, unlike, for example, with the Ayon CD-35 HF Edition, I did not have the impression that these DSD files were the right ones. I will say more - for me, PCM files sounded on it particularly accurate and natural; this also concerned CDs being listened to via the RCA S/PDIF input. The sound was then open, strong, extremely detailed and natural.

The tonal balance of this converter is slightly shifted upwards and this will be one of the basic determinants, in my opinion, when choosing the right digital filter (see box below). This shift is, however, a part of something bigger, it's not about sound being too bright – it's something completely different. The sound is very open, detailed, it has proper drive and energy - these are basic elements the whole performance is built on. It is not a warm sounding device, nor a soft one. Admittedly, when switching to DSD1024, the attack is somewhat softened and the bass becomes warmer, but this is not the best way to use this DAC. With an apodizing filter or without oversampling, we can get a much more realistic sound, and at the same time more accurate.

iFi shows large phantom images, has proper momentum and sounds in a very direct way. This was the case with older hi-res PCM and DSD recordings, as well as with new LPs with quite high compression. The directness lies in the fact that the energy of the foreground, its "here and now", are unique. Perhaps not everyone will like it - if someone prefers a more distant presentation, more "in the back", the Pro iDSD can be too “forward” for him. There is a lot going on here, the sound is active and powerful.

The bass extension is not spectacular, but I never felt like there was not enough bass or that it didn't go deep enough. This part of the band is well controlled, compact and taut. It is not too saturated, it is not a device of this type. It's just meant to be a solid basis for the midrange, because it's the sub-range that has the most to say here. By switching to files with a high sampling rate, i.e. 96 kHz and higher, the saturation improves, but it does not change the overall picture.

And above all, it does not change my appreciation for the designers of this converter. On the one hand, we get a very neutral and accurate sound, because that is a starting position in the recording studio, and unfortunately it often ends there. On the other hand, it is a very natural sound, mainly due to the depth of the sound and its richness. I would be careful with systems with a rather dry sound or those in which high tones dominate. This can be too much when combined with Pro iDSD. It's a converter that does not lie to us. With its help, we will not correct anything, nor save poor sounding recordings. It is supposed to be a kind of wide open window from the source side, that allows us to look through it without a risk of “seeing” fake reality.

Tidal

Last but not least, shortly about the Tidal, that deserves its own paragraph, and even three. iFi presents the sound in a very accurate way, so the warming and rounding of the sound disappears, which I heard both with Lumïn working as an integrated player, and when I listened to it as a transport working with the D/A converter in Ayon CD-35 HF Edition. It is very accurate sound, and at the same time extremely dynamic.

Recently, the album of the Urbanator Days group was released, called Beats & Pieces, animated by Michał Urbaniak and recorded by him with young hip-hop artists. It is simply sensational! And really well recorded too. iFi fantastically conveyed the low, energetic bass and beat on which these songs are built. The presentation was equally dynamic and energetic with another new, also very good Polish recording, ie with Kuba Badach Oldschool - I'd like to recommend it to you! There was no exaggeration, just accuracy, confirmed during listening to Another Raindrop by Kuba Więcek Trio, the number 78 in the Polish Jazz series.

It will sound even better with tracks encoded in MQA. It was with the Pro iDSD that for the first time I heard such a big difference between them and the regular FLAC files. Recordings encoded in MQA sounded smooth, fluid, like DSD. So users of this device will look for such streams. They eliminate the slight brightness of midrange, which with strongly compressed recordings - for example Melody Gardot and Eminem - are a bit “too strong”, exaggerated. It does not take away the pleasure of listening to them, but when one plays the same album in MQA, one immediately appreciates the more natural sound.

| Headphones

Headphone amplifier implemented in the Pro iDSD delivers a nice, well-balanced sound. It was powerful enough to drive all the planar headphones I had at home including the HiFiMAN HE-6 without any problems. With the latter, I had to switch the "gain" to +12 dB position, but that's what the switch is for. With the HE-1000 V2, +9 dB was enough to make high definition files, including DSD, sound loud and dynamic.

Listening to the music felt extremely comfortably. This is a device, that does not try to beat the headphones connected to it in terms of resolution, after all that what the class A Pro iCan is for, right? But to know this you need to have a high-class external headphone amplifier, for example, as mentioned in the "test methodology" section, the Ayon Audio HE-3 or Octave V 16. Without such references, listening to CDs, files, Tidal stream – or in short to anything at all - the iFi amplifier will be a great companion in your music adventures.

On one hand it is an open, powerful, energetic sound but on the other it is also creamy. The sound attack is slightly rounded and smoothed out. But also leaning “forward”, so to speak, i.e. giving the track a proper rhythm and compactness. The tonal balance is shifted towards the midrange, there is not too much saturation of the lower midrange and the upper bass. But, as shown by the 24/192 2xHD sampler, the bass goes deep and is well controlled. Also, with the Anja Garbarek's Briefly Shaking album CD rip, that includes the Sleep track with bass going very low, with high sound intensity, the HiFiMAN cans sounded powerful and without compression.

Summarizing this part, let me say that the headphone amplifier in Pro iDSD is a valuable component of this device. It is not its main element, but it would be idiotic to call it a simple "addition". It conveys the changes in the recordings without a hint of hesitation and I it allowed me to enjoy once again Aga Zaryan from the Master WAV 24/96 files, and then to compare tracks from the Polish Jazz catalog before and after the remastering (Master WAV 24/88.2). Songs played from Tidal sounded also quite well - maybe even best. The powerful, directly communicated by iFi midrange, also its upper part, was counterbalanced by the warmth and roundness characteristic for this streaming service. In short – it sounded really good!

Summary

When assessing Pro iDSD, I referred mostly to the performance of the digital-to-analog converter and, to a lesser extent, the DAC cooperating with the built-in headphone amplifier. In both cases I got an extremely satisfying sound, which included everything I demanded from a digital source, i.e. precision and immediacy, but also large volume and density of the sound. You will find other devices on the market playing deeper, with a more elaborate sound stage, with a stronger bass, but almost always these qualities come at the expense of resolution and differentiation, which - for this price range - are fantastic with the iFi converter. Well deserved RED Fingerprint Award!

The iFi Pro iDSD digital-to-analogue converter has a width slightly smaller of a half of a professional rack and it is slightly higher than 1U, i.e. the basic section of such a rack. A standard 'Rack' has a width of 19" (48.26 cm) and a height of 1¾" (4.445 cm). The device received a very solid housing made of aluminum used in the aviation industry. The top and sides are not flat, but wavy, which looks very good. Inside, on the bottom, the housing is loaded with a metal plate adding weight and a vibration damping material with a honeycomb pattern. The device has no classic feet but instead it features a large piece of a soft cloth.

One can find some inspirations in the visual design taken from products made by other companies, but the whole thing is something new and looks very nice. For example, a round “window” with a display resembles what Marantz once proposed in the SACD SA-1 player, and then used in other products. In turn, the eye of the magnifying glass on the top wall through which the interior of the device can be seen - in this case tubes - was promoted by Chord Electronics in the Hugo TT. And finally, the illumination of tubes - they do not glow strongly by themselves, that's why many manufacturers highlight them with LEDs, which is what McIntosh excels at. They use green color, and iFi prefers orange.

Front

The display in question is very helpful and clear - it's an OLED one. On the left there is the input selector and upsampling knob, also functioning as push-buttons. Under one of them there is a small toggle switch that allows user to choose an output mode. With the same switch, but placed on the other side, under the 6,3mm headphone jack, one changes the gain of the headphone amplifier.

The three headphone outputs actually - there is also a 3.5mm minijack and 2.5mm TRRS microjack. It features four rings and supplies the headphones with a balanced signal. It is a pity that the company did not use the large Pentaconn balanced connector instead. This is a type of balanced plug developed by Japan Electronics and Information Technology Industries Association (JEITA), already approved, among others by Sony and Sennheiser. More HERE.

Rear

As one would expect from such a small device, the back of the device is packed with connectors. The digital inputs are grouped in the middle - the RJ-45 socket, USB for external hard drives, Audio USB for computer signal, AES/EBU, RCA and BNC. Interestingly, there is no optical input. There is also one more BNC socket – an output of a word clock – the Pro iDSD can be part of a digital system clocked using one word clock - either the iFi's build-in one or external. There is a switch that allows user to choose between these modes. Let's add that there is also a connector for a Wi-Fi antenna and a Micro SDHC memory card reader slot.

There are also two pairs of analog outputs: XLR and RCA. The RCA sockets feature gold-plated ground, but not a signal pin. The both types of outputs can deliver standard signal for home systems, i.e. 4.6/2.3V (XLR/RCA respectively) or a standard one for pro systems, i.e. 11.2/5.6V.

Inside

The electronic circuit has been assembled on three boards: one with D/A converter, smaller one with USB input, file player and Wi-Fi module and a longitudinal module with power supply, ie. DC/AC and AC/DC converter. Tmost elements are surface-mounted (SMD), but large filter capacitors are threaded.

The main PCB features the DAC - these are four PCM1793 chips operating in an unusual system, that allowed designers to bypass the limitations of the DACs regarding the upper sampling frequency. The company calls this mode of operation "interleaved". These systems separately convert PCM and DSD signals separately. Both first are go through digital filters. These were implemented in a powerful Crysopeia FPGA hidden under a large heat sink - this part is just like a microcomputer. The converter work in "voltage" mode, and the signal after them is filtered passively in third order filters.

And finally, there is an attenuator. This is a classic rotary potentiometer made by the Japanese Alps. It features as many as six rings, because an unsymmetrical and symmetrical signal are carried out separately. There are two JAN 5670W General Electric double triodes, one per channel. These are NOS type tubes, originally developed for the US Army (JAN = Joint Army-Navy). In this case, it's a "black plate" version, better than the basic one, and "W" in the name means a long-life tube. If necessary, they will be easy to buy and affordable – they cost about 23 USD a piece.

Next to the tubes there is another amplifying circuit, featuring the J-FET transistors in the input and bipolar ones in the output – one can choose between them using the switch on the front panel. This is a system without capacitors in the signal's path. Let me add that the headphone output is powered by an elaborate transistor circuit. At low levels, it works in Class A, going to the AB class with a more demanding cans.

The USB input features the XMOS chip, which works with the Spartan-6 DSP chip. This input, just like all other ones, is galvanically isolated. What's more, the signal from all inputs is oversampling, which helps to minimize jitter. This system, called "Global Master Timing", comes from the DP-777 D/A converter from the Abbingdon Music Research (AMR), iFi's mother company. The XMOS circuit also features an audio file player function.

The DC/AC converter PCB is particularly interesting. It's just a power conditioner. The first power section is a classic SMPS that resembles computer power supplies, and it is connected to the converter with a short cable. It provides a 15 V/4 A current. Based on this voltage, the system in question generates a pure high frequency sinusoid. It is rectified and goes to the filter with the inlet choke. This section produces, additionally stabilized, supply voltages for each section of the converter. The power supply for the USB section is galvanically isolated.

The voltage for the digital section is filtered using high quality Elna Dynacap DZ capacitors with a total capacity of 6.6 Farads (6,600,000μF!). These capacitors have an internal impedance 400 times lower than classic capacitors. The voltage is regulated in precision TI LDO systems with local LC filters. There are six separate power supply lines. The voltage for the analog section is additionally stabilized in the OV2028 operating circuits. The voltage for tubes (60V) is separately generated and filtered in Elna Silmic II capacitors.

Specifications (according to manufacturer)

DAC
Audio formats:
- DSD 516/256/128/64
- DXD 768/705,6/384/352.8kHz
- PCM 192/176.4/96/88.2/48/44.1kHz
- MQA 192/176.4/96/88.2kHz
Output voltage (XLR/RCA):
- hi-fi 4.6/2.3V
- pro 11.2/5.6V
Dynamics: 119dB (solid state, PCM)

Headphone amp
Output (16Ω):
- balanced > 4000mW
- unbalanced > 1500mW

General
Power consumption: 22W (idle) | 50W (max)
Dimensions (W x H x D): 220 x 213 x 63.3mm
Weight: 1980g