iFi Audio iTube

As a beginning, I would like to thank Owen and Karina from iFi iClub for lending me this product.
 
To provide some solid base, here I leave you some information about my music tastes and my brief journey in audio.

 
 
 
Now, into the review, don't you love its warm orange light? I'm in love with it.
 
 
BUILD QUALITY

 
It comes packed in the famous iFi case, sign of "micro" range, with the same finishes as always. Robust switches, gold-plated connectors and their own-designed potentiometer improving the so acclaimed ALPS.
 
 

 


 
A nice quality board, with 4 layers and top notch rails and great quality resistors and capacitors. Such a beauty!
 

 

 

 
 
If we look at it upside down, we can see 8 DIP switches that allow us to select the gain (0dB/6dB) and whether using it as a pre-amp or as a buffer with the help of a flat screwdriver (like the one included). 
 

 

 
I already put the silicone feet to use it in my table more confortably but to my surprise, they changed them in favour of some smaller ones with an elegant logo. With these I no longer can workarround a way to stack them. But, in any case, for stacking iFi micro/nano devices, iRack is the best choice.
 

 
INTO THE EXPERIENCE
 
This little gem takes about 20 seconds to wake up, that's how valves work. I encourage you to wait until it is ready (look at |> led indicator).
 
We plug two pairs of RCAs as input and output and we are ready to rock. I have used the included cables by iFi which offer a respectable quality. No complaints.
 

 
 
It is now the moment when magic breaks in, mildly sparkles the elegant and impressive General Electric 5670, also sold apart by iFi for 6922 socket valve devices making use of a tailored ceramic adapter adhered to the valve. Top notch stuff! (More info here http://ifi-audio.com/portfolio-view/accessory-nos-6922-2/ )
 

 

 

 
Speakers engaged, we crank up the volume and we get lost in music... Guitars sound uncompressed, the piano flows dynamically, voices gain texture... Overall a nice effect.
 

WHY A TUBE BUFFER IMPROVES SOUND QUALITY?
 
I'll try to get into the reasons why this improves musical joy:
 
First, considering it is an active buffer/preamp, some of the spice comes from the 9v iPower SMPS (Switched-Mode Power Supply) which powers this 5670 with very low noise (1uV). Power supply improvements affect noise floor and dynamics.
 
The second reason of improvement is impedance matching. With its enormous input impedance of 1 Mega Ohm when used as a buffer and 100 kilo Ohms when used as a preamp, it fixes any possible impedance mismatch between source and amplifier. 
 
But let's get into business, we are here for the vacuum tube. It's been said by many audiophiles that tubes introduce distortion (harmonic, but they do) in an excessive manner but on the counter-part, tube fans claim solid state sounds unnatural due to odd-harmonics (IMD). So, who is right? Both! But in this particular case, iFi has deployed a very neutral and clean tube, with very low levels of harmonic distortion. The sound we get out of it is almost no colored but it provides a smooth musical experience, helping with some compressed recordings and staying true to original with uncompressed well recorded tracks.
 
 
Bass feels more real and has a slight bit more of dynamic. Overall, it has better texture.
 
Mids flow wonderfully, giving a very pleasant experience. Very smooth.
 
And highs stay neutral but less fatiguing when using bad recordings.
 
But I can assure you one thing, you will enjoy your music with this bad boy. For granted!
 
 
 
DIGITAL ANTIDOTE+ AND 3D HOLOGRAPHIC ADD-ONS
 

As a side note, I want to mention that Digital Antidote+ helped me masking out a "compressed sound" problem I had with the USB cable I was using with my micro iDSD. Fortunately I have already changed it in favor of an Oyaide neo d+ USB Class S, which not only solves this but improves SQ noticeably, but this is another topic... With this cable, this feature does no longer add a significant improvement with my micro iDSD (I think it does something similar to Minimum Phase filter, correct me if I am wrong)
 
 
And the last feature worth mentioning is 3D Holographic. It provides an outstanding improvement with bookshelf speakers, making them feel more spacious and bigger sounding. There are two modes: Low (*), for HiFi speakers, High(***), for bookshelf speakers and off. So you can find the one that suits you best. I used High(***) mode.
 
 
 

 
CONCLUSION
 
As a recap, this device is a nice addition to almost any setup, from Mid-Fi to some pricey Hi-Fi. Adds smoothness and joy to your music, pleasure is guaranteed!
 
I will leave you some more photos for you to enjoy 
 

 

 

 
 
   

Product name: iFi Micro iTube Tube Buffer/Tube Pre-Amplifier
Manufacturer: iFi
Cost: $329 US dollars.  Provided as a courtesy via iFi Customer Service for evaluation with my currently-owned (All Purchased) iFi equipment .  No incentives given or accepted.
 
Reviewer: Ken Norris - North America, USA, New Jersey
Reviewed: March, 2016
 
 
So, a little over a year ago now, I bought and reviewed a USB DAC from iFi called the iDSD Micro.  Spoiler:  I LOVED IT!  While I am admittedly a relative newcomer to seriously pursuing the ever-moving target known as "Audiophillia", it seems that I have fairly decent luck when it comes to picking people to learn from.  After listening quietly for quite a while to what others who have gone before me had to say, I took the plunge and haven't looked back since. It also turns out that the iDSD is just one device in a whole lineup of products that are designed to work and fit together as the "Micro line" of iFi components. After evaluating the iDSD, and iCAN, I now turn my eye (and ears) towards the iTube in this review.  So what is it?  The iTube is a valve pre-amp that is designed to work harmoniously with the other iFi Micro devices.  I also learned coincidentally, that it works equally well with other brands, but the form-factor is quite literally MADE to fit with the other devices in the iFi Micro line which just makes the whole audio stack affair look so "clean", that even my wife who HATES clutter/wires/gadgets admits that the lineup looks like some kind of industrial art centerpiece.  (Fair warning, I added some "cable management" to tidy-up the power cords!)  To me, a major benefit of the entire MICRO line is that I get serious, full desktop-sized component performance and sound that doesn't ACTUALLY take up a whole desk!  (All 3 MICRO components fit neatly in my backpack or laptop bag for my "on the go" lifestyle.)
 
The review:
 
For starters, the iTube that was shipped to me courtesy of Owen & Karina D. (Rockstars in customer service) arrived in the same iFi-Standard packaging as the iDSD & iCAN did. The box dimensions are all identical which makes for easy bulk-wrapping if giving the set as a gift.  (Very thoughtful!)  
 
Layout - On the front panel is a volume knob and a 2-position switch for Digital Antidote Plus® and another for 3D HolographicSound®.  On the rear panel there are two pairs of RCA jacks for analog audio input and output.  The power socket is on the right-side panel (Looking from the front), with the power supplied from a wallwart power supply with integrated iPower technology to reduce signal interference.  As a nice touch, an L-adapter cable is included so that the power cord doesn't have to stick out of the device at a 90-degree angle!  Underneath there are the pre-amp/buffer preset DIP switches that allow you to select operational modes. This allows you to not only determine how the unit passes or modifies signal, but also how much of an influence the tube/valve circuit will have on your end sound.
 
What does it do?:
The iTube contains two primary switchable circuits. The first is the 3D HolographicSound® system which provides to my ear, a more 3-dimensional effect to the music and slight highlight of soundstage separation.  The second switch is called the Digital Antidote Plus® whose purpose is to soften any harsh, "ringing" digital sources which contribute to "listening fatigue".
 
Does it work?:
In my trials, I primarily used the iTube in series with my iDSD as DAC, RCA'd to the iTube, through to my iCAN.  I sometimes substituted-in my Schiit Audio ASGARD 2 or my ONKYO HT-R693 (Via Phono RCA-in jacks) as amplifiers.  Beautiful in every configuration.  Most importantly, I switched-off between my iBASSO DX90 (Coaxial digital signal into the iDSD) and my Home Theater PC (Windows 10 i7 via USB3 digital signal.)  Why most importantly?  Because I was sampling digital audio files ranging from low bit-rate MP3s through DSD128 via straight digital SPDiF & USB transport methods.  If there is anything that I've read that can indicate a cold, sterile, or harsh sound, it's a pure digital setup amped by solid state.  Now does it ever happen to me?  Heck yes!  I've got an abysmal sampling of Foreigner's "Agent Provocateur" that I ripped from my CD back in college back in the 80s that is my personal BENCHMARK for horribly-sampled sound. Scratchy sound quality with grossly-obvious artifacts throughout.  Even my Sennheiser HD-650s were unable to make it sound good!  Now am I going to tell you that the iTube made it sing like a choir of angels?  NO.  What is lost in sampling can normally never be brought back.  But the inclusion of the iTube DID make the darn tracks sound "listenable".  (Think of going from an old, static-laiden AM band radio to a decent mono FM radio.  Still not what you are used to, but definitely a sight better than what you had!)
 
So, WHY did I start with that example?  Because the point is that the iTube is a very transparent component in the audio chain. It didn't matter if I was using it in pre amp mode, buffer mode, or even with the effects on, the music remained clear, clean, and mostly unaltered. I ran bit-perfect all the way to this device, and it never did anything weird or unexpected to the sound. So I say all that about the worst-case scenario above because it was the only way that I could CLEARLY tell the difference between before & after with almost no effort.  (And I was using Beyer-Dynamic T1 ver. 2s, & Sennheiser HD-800s to check!)
 
Under "normal conditions" I listened to, and loved some sample  tracks that were recorded in NATIVE DSD128 from InterDA Music (http://www.interda.com/)  These "LIVE" recordings allowed me to examine everything from side conversations in the audience, to the scrapes on the floor as instruments were shifted and moved during performances.  TONS of detail.  Not much by way of sibilance, but when you can hear air moving, you know when you're losing detail due to masking.  With the iTube in or out of the chain, I still heard ALL the effects!  It was to me, the difference between a strong knock on your door that startles you, and a strong knock on your door that you are expecting.  No less loud or crisp, but not as jarring.  (There is an audience member who yells, "Whoo!" in the very beginning of the track "Light My Fire".  You can still hear her and others make various sounds in the background throughout the song, even when the brass do their staccato hits.)  Is it harsh with all that detail?  No.  But it just sounds slightly more welcoming, and enveloping when the iTube is in the audio chain.  And that is the point.  SLIGHTLY.  Not night and day, but if you are actively listening, the added warmth IS there to enjoy.  And I do!
 
Equipment:  Sources - iBASSO DX90, Samsung YP-P1, Dell XP 8700 (i7, Win 10, Foobar 2000 ver 1.3.5, JRIVER Media Center 21, TIDAL (Client & Browser players), Amazon Music Player, VLC Player, Groove Music Player, & Windows Media Player) Apple iPad Air (ONKYO Player App), Apple iPhone 4S, 5, & 6 phones (ONKYO Player App)
 
DACs - FIIO e17, iBASSO DX90, iFi iDSD, ONKYO HT-R93
Amps - Schiit Audio ASGARD2, iFi iDSD, iFi iCAN, ONKYO HT-R693
USB Signal Conditioner - iFi iPurifier2
Cables - Monster HDMI, "Generic" USB, Forza Audio Works Digital interconnect, iFi-provided RCA patch cables
Headphones - AKG K545 & K550, Beyer-Dynamics T1 (ver. 2), JVC ESNSY - HA-SR85S-T, HA-SZ2000, Sennheiser HD-650 & HD-800
IEMs - VMODA bass freq, Sony XBA300AP, Sennheiser Momentum
 
Conclusion:
 
Would I buy?  Yes.   But bear in mind that I only found value myself when ACTIVELY listening.  (Others may very-well notice more easily than I...)   Would I use it during a morning commute?  No.  To listen to generic "top 40" background noise while doing chores around the house?  No.  I just wouldn't be paying enough attention to notice the difference.  But to relax in my easy chair and just enjoy seriously listening to some truly great music?  Definitely.  Why 4 1/2 and not the full 5 stars?  Well I want to leave some room for the next piece of kit iFi develops that will by all previous examples, improve all of their current offerings considerably!

Having the iDSD Nano & iCAN Nano from them, i was very impressed by the iFi's performance. 
Making me trust my money to them, knowing they can provide what they claim it could, and deliver them so beautifully, sonically.

First thing i noticed when i held the iTUBE in my hand , i immediately noticed it was significantly lighter than the iDSD Nano and iCAN Nano , which felt pretty weird . Then i realised that the iDSD Nanoand iCAN Nano both have batteries in them, making them denser. In my opinion, the denser ones felt more premium as there's a certain quality feel to them.

That aside, the iTUBE also require a 3 pin power source, making them desktop bound.

I ran them as such;
Laptop(FLAC 16/44.1 & 24/192) > iDSD Nano > iTUBE Micro > iCAN Nano > Beyerdynamic T90

Alright , the positive points , upon setting up and warming them up , I took a while to play with the switches to try what each of them actually do to my music , but before I did so , I realised my there’s already a slight smoothness in my music which makes them quite enjoyable .

Flipping the Digital Antidote switch did little difference to my music , in all honesty , I could not hear much difference , but I have heard other reviewers stating that it allows mp3 files to sound better , im not sure , I do not hold a single mp3 file in my music list . Having said, I believed it does “significantly reduces ringing and digital distortion” as claimed by iFi & a placebo effect and trust in iFi has quite urged me to leave it on. If you are going to play poorly recorded file with sizzle, cracks and pops and expect the Digital Antidote cancel these flaws away, it won’t.

Then I flicked the 3D holographic to “wide” & “ultra wide” settings , surprisingly , they were not as satisfying as the iCAN Nano’s 3D holographic on my headphones , they felt different , even if I switched my iCAN Nano’s 3D OFF , and the iTUBE’s 3D ON , it still sounded different , very different. But before I make any conclusions, iFi website did mention that the iTUBE’s 3D wide was meant for Hi Fi Speakers & iTUBE’s 3D ultrawide was meant for desktop speakers. With that being said , it is unfair to conclude that the iTUBE’s 3D was of poorer quality than that of the iCAN’s , I have not tried them on speakers , but again , other reviewers online did mention that they found their speakers to be producing addictingly good soundstage with the iTUBE 3D settings , I decide to leave that setting at “zero”. Again, on headphones the iTUBE’s 3D sounds different as compared to iCAN’s. It is wide, but in a manner perhaps not meant for headphones.

The tube glows red and the aluminium case is warm to the touch and works comfortably well as a finger warmer in the cold. The settings was set to “0Db Buffer” , I adjusted it a few times back and forth to the “6Db Buffer” to compare their differences and noticed the 6Db buffer had a more warm and tubey sound , which I have found to love a lot . This changes the characteristic of the music, making it smooth like a warm cup of cappuccino, extremely satisfying & comfortable, Immediately, I know, this is something which I am going to enjoy for a long time. This is really up to preference but I like the 6Db buffer setting better. Sonically, it does not colour the sound much to make it sound choked, it does maintain its integrity. I’ve tried other critically acclaimed tube amps such as the Ocean Bravo which I feel is too coloured/ choked at the high frequencies & losing some of the soundstage & instrumental imaging from the iCAN Nano’s 3D holographic, since music is about preference, I enjoy the iFi iTUBE better as I moved to tubes, from a full solid state setup. But in all seriousness, if you haven’t got the iCAN Nano, please do get it. The performance is superb.

Speaking of those little white gain switches at the bottom. I broke my number 5 switch which is one of the switches that sets the 0db & 6db buffer. This was the only flaw I’ve discovered and was quite disappointed, however I will be heading down to one of their distributors which I have purchased them from to see what can be done to it. Other than that, the construction quality seems durable & solid. 

I've changed the iTUBE for a new one today & redeemed warranty now im a happy potato !

In conclusion, this is a very good buffer that makes your music really smooth and enjoyable. If your budget isn’t an issue, this is definitely a tube buffer worth considering. Don’t forget about the iCAN too! 


Here is my setup !

The Campbell coin bank was used to manage the cables

  I would like to thank Vincent at iFi for sending me this sample for review,
 
I’m a fan of IFI products. I have loved their dac and usb power supply (here is my review) so i have decided to
give a chance to the lastest product from the Micro line, the IFI iTube.
But first, who is IFI?
Ifi is a young English company with trickle-down technology licensed from AMR (AMR is a producer of Hi 
End valve components). Recently they released their new Nano line dedicated to portable listening which 
includes the battery supplied iDSD, a very interesting portable DSD dac, and the iCAN Nano, a portable 
headphone amplifier.
 

 
 
The iTube it’s a very unusual component, it’s a valve buffer stage that can be used also as a preamplifier 
which can be added to audio chain between the dac and the dedicated amplifier for our headphone. The 
goal is to remove from your setup the “digital and metallic” sound and reach the famous tube sound without 
losing the detail and dynamics that are typical of a digital system. 
Will the iTube sound good as the other IFI products?
 
Test setup

 
Source: PC with Jmedia River, Resonessence Labs Concero HD, Dragonquest Audiofly
Amplifier: Schiit Asgard, Questyle CMA800R
Headphone: Sennheiser HD650, Denon AH-D2000, Heir Audio A.4i, Hifiman HE500
 
Tech specs
 
Input voltage: AC 100-240v, 50/60Hz
Power consumption: <4W Idle, 10W max
Input impedance: 1M ohm Direct Tube Buffer
100k ohm Pre Amplifier with Volume Control
Output stage output impedance: <1 ohm
Corrected output impedance: <200 ohm
Dimensions: 175(l) x 67 (w) x 28 (h) mm
Weight: 278g (0.61lbs)
 
Packaging
 
The packing is the same of the other product from Micro line. Inside is the iTube, a power supply marked IFI 
and his extender, a couple of RCA cables, a small screwdriver that you will need to change the position of the 
little switch and four silicon feet.
 
Construction

 
The iTube shares the same good casework of the other products from IFI Micro Line. We have been really
impressed on how IFI it can put a valve in a such small case (175(l) x 67 (w) x 28 (h) mm).
The case is all made by aluminium with silver color and the assembly is good.
On the upper part there is the IFI logo printed, but instead of the dot on the “i" you find a small hole from 
where you can sees the light of the tube, a really nice thing. Another difference is the power supply hole on 
the side of the case. This is the only position allowed on the case, the two front panels are already full of 
connectors and switches.

 
Under the iTube there are 8 small switches that allow to choose between the four functions:
- Buffer stage with no gain (0 dB)
- Buffer with gain (6 dB)
- Preamplifier with no gain (0dB)
- Preamplifier with gain (6dB)
Next to the switches there is an illustration of their position to allow the various functionalities.
The gain function can be used in case of low output voltage source, but if the source has a standard 2 V exit 
it’s better to use the iTube with no gain.
On the iTube the input/output position is better than on the other Micro products, they are all on the same 
side. The four connector (2 pair of RCA) are very near but I didn’t have a problem with big connector like one 
of the Audience 24 s cables.

 
On the opposite side there are two curious switches and the volume knob. The knob it works also as an on/off 
switch and it doesn’t effect the volume if you use the iTube as a buffer.
The two switches turns on two patented circuit: 3D HolographicSound® and il Digital Antidote Plus®.
The first it can be set on three positions and it allows to increase the sound stage.
The second it can be set to two positions (on/off) and it can remove the digital signature and the digital
distortion.
The power supply is marked IFI and it’s a super low noise supply with a 9V and 2 A current.
After we have removed the two front panel it’s possible to take a look on the inside. The tube use by IFI is 
a NOS General Electric 5670 which is welded to the base. Don’t worry its life is evaluate in 100.000 
hours. The valve is parallel with the board. The board is divided by some white lines and every sector 
its marked with its function with a white writing. 
 

 
 
How does it sound
 
The best use of the iTube is as a tube buffer. The pre amp function has to be used only in case you don’t have 
a analogue volume on you amplifier so you can avoid using the PC’s digital volume. This review is focused on 
the buffer function.
The first time I had put it in my setup i didn’t know what to expect.
The first surprise was that iTube is noise-free and it lack the typical swish of tube components.
After i connected it up, I expected a strong frequency response change with a fatter bass and a lower detail 
and dynamics, but this didn’t happen. The iTube added only the best virtues of “tube sound” and the result 
is a more musical and warm sound, but the basic sonic signature of your setup it will remain the same.
The result is remarkable special with low end dacs that will lose their digital and metallic sound to enable 
them to perform much better. The iTube can also enable low quality files sound better. I have tried to 
connect the itube to the integrated sound card and the improvement was awesome. With high level dacs the 
improvement was less impressive, but it still makes their sound better anyway.
The 3DHolographicSound® is a really nice feature and it can increase the sound stage with a wider 
presentation. If you choose the lower level the sound stage it will be the same of your source, at level 1 the 
difference it will be a little difference but at the level 2 the soundstage it will much wider with the sound that 
seems to came from the outside of the headphones and with a lower congested sound . I have connected it 
also to my speaker and the effect was also better, especially with nearfield listening.
The effect of the Digital Antidote Plus® is less noticeable and it depends by the quality file and dac quality. 
In case of old style Upsampled or bad dacs, it removes the metallic sound but if you have a recent or a Nos 
dac you can turn it off. A good improvement can be noted if you use low quality file, like YouTube or Spotify 
recordings.
 
Conclusion
 
One again, IFI has impressed me.
This small buffer will add a fuller and warmer sound to your setup and also poor components made more 
enjoyable. With its preamp function it can be used instead of the digital sound of the PC with a better sound 
quality and with the gain function you can use low output voltage sources without any issues.
The 3D HolographicSound® will increase the sound stage and the Digital Antidote Plus® will remove the 
sense of digital from lower quality dacs or audio files, but it’s quite aimless with modern dac..
The build quality is good and the production engineering is fantastic, putting a tube in a such small case isnt’ 
that easy.
 
Summary
Score: 9 su 10
Pro:
- Good build and product engineering
- A loto f functions
- It adds the “tube sound” without any weaknesses
- Excellent 3D HolographicSound®
- The tube life is estimated at 100.000 hours
- The iTube will increase a lot the performance of the old dacs
Contro:
- The tube can’t be changed
- If you use with extremely big RCA connectors you may have spacing issues
 
Source: Stereo Head

iTube is the latest addition to iFi Audio ‘Micro’ line of audio gears. On one hand, it inhere the same minimalistic concept as the other Micro gears; on the other hand, it is a departure from the previous all-solid-state design. If anything, it is the first in Micro gears that will appeal more toward speaker user rather than headphone user. So what exactly does an iTube do? In essence, it is a tube buffer / pre-amp, with some extra features threw in.



Spec
Input voltage: AC 100-240v, 50/60Hz
Power consumption: under 4W Idle, 10W max
Input impedance: 1M ohm Direct Tube Buffer / 100k ohm Pre Amplifier with Volume Control
Output stage output impedance: less than 1 ohm
Corrected output impedance: Less than 200 ohm
Dimensions: 175(l) x 67 (w) x 28 (h) mm
Weight: 278g (0.61lbs)
MSRP: US$299





Gain - Buffer or Pre-amp
Like the newer iCAN, there is a user selectable gain switch on the belly of the housing. However, the switch also enable / disable the volume pot on the iTube, allowing it to run either as a Class A tube buffer or a pre-amp. In both modes, you can also choose either zero or +6dB gain, depends on how strong your source’s signal is. Of course, you will have to take into account whether the output will clip the input of the next device (which will be an amp or an amp section on an active speaker). My suggestion is, if your source has a 2V line level signal or something near it, keeps it at zero gain. If your source has a weak signal (i.e. older iPods only have only a 0.55V line-out), gives it the +6dB gain.

As for whether to use it as a pure buffer or pre-amp will depend on the gears you are connecting the iTube to. If it is feeding to a power amp that has no volume control of its own, then obviously you should use iTube in pre-amp mode to control the volume. If however the iTube is feeding into an active speaker that has its own volume control, then iTube should be configured as buffer. Note that the volume pot also doubles as the on/off switch, so you still need to turn it on even in the buffer mode, though volume will not be changed at all. As with all tube gears however, you should try to avoid rapid or frequent on/off action as much as possible in order to prolong the tube operational lifespan. If you are only going away for a short while, instead of turning it off, it might be better just to leave it on.



Sound Quality
Tube is always associated with noise and harmonic – in a way iTube is about those as well, but more on the harmonic and less on the noise. For measurement, I set the iTube up in a full iFi chain – staring with iUSB Power, which connected to the iDAC via the Gemini dual head USB cable. The line-out of the iDAC is fed into the iTube as a buffer, then to the iCAN with a 23.5 ohm dummy load. RMAA measurement is done with both the iTube in chain and without it for the comparison. Surprisingly, the impact of iTube, at least on graph, seems to be fairly minimum. Yes, it is noisier with the iTube, but we are talking about 0.001% of difference in THD and 0.004% in IMD+Noise, plus less than 2dBA in overall noise level. The numbers are small enough that I have to wonder how valid they will be in actual listening. As far as the frequency response goes, iTube is as flat as it can be, at least when the Digital Antidote Plus is not engaged (*but we will leave that discussion to the next section).

The actually listening experience with iTube however is a much less subtle business. Beside the setup mentioned above (plus a pair of Sony MDR-1R and a few IEM), most of my audition of the iTube is done in buffer mode with a pair of Creative GigaWorks T40 Series II 2.0 desktop speaker with an additional Creative sub-woofer. The first thing to pick up with the iTube, and particularly noticeable with headphones, is the distinctive ‘tube’ sound. So what is this tube sound? Well, it is a general richness that isn’t there before, like switching from a standard definition to a high definition signal on TV. It is the same image, but there is more information that fills up the space. At first, the effect is not that apparent. But once I switched back from iTube+iCAN to iCAN only, and just like going from HD to SD signal, everything sounds duller and harsher, even though I have been enjoying iCAN by itself for months now. I guess this is what iFi has referred as the ‘voodoo’ of the tube sound - the kind of euphonism that is just hard to get rid of once you are hooked. This is probably what makes tube gear user return to tube time and time again.



EQ
There are two additional features that are packed into the iTube – the 3D HolographicSound (3DHS) System and Digital Antidote Plus – well, calling the Digital Antidote Plus an EQ might not be the most accurate, but just bear with me here.

Don’t confuse the 3DHS on the iCAN to iTube. Yes, both have the same name and supposed to enhance soundstage, but that’s just about where the similarities end. The 3DHS on the iCAN is tuned with headphone in mind, but the one on iTube is all about speaker. The ‘small’ setting is meant for floor speakers or monitors that are already placed far apart and the goal is to put out a better perceived separation on the lower frequency region. The ‘wide’ setting however is meant for desktop monitor (such as PC speaker) and is aimed to project a bigger overall image than the speaker usually can. You can of course choose whichever setting that fits your own speaker configuration and taste, but I do find the wide setting does show significant improvement over my T40 S-II (which is a desktop speaker). In a way it does a similar function as the software based virtual surround sound effect built into the Windows OS, but much better in result. While Windows (and a good number of software movie players) tends to try to create a more hollowed out image between the left and right speakers to create the illusion of space, the 3DHS ‘Wide’ on iTube is more about pushing out an image larger than the speaker’s physical placement, as if they are actually further apart. This works out better for music listening as the mid-range still retains its texture and intensity as opposite to a hollowed out sound. As with the 3DHS on iCAN, I am quite amazed by iFi ability to fine tune the analog circuit and be better than software solution. But the one thing to note is that this 3DHS is for speaker only. Trying to use it with headphone will mostly mess up the image instead of improving it (same can probably be said on iCAN’s 3DHS negative effect on speaker).



Digital Antidote Plus on the other hand is lesser of an EQ and more of a phase correction technique for digital source. The original idea of a ‘digital antidote’ comes from and patented by Anthony Taddeo of Taddeo Speakers in the early 90s to address the digititis of then popularized CD system. In simple terms, it involves splitting the analog signal from a digital source into two, delays one of them with a few milliseconds then recombines it back to the original signal in order to correct whatever phase error introduced in the digital stage and to recreate a ‘more analog like’ music reproduction. It had caused quite a stir in the audiophile’s community when it was first introduced, both positively and negatively, where some swear by it while other found the effect to be subtle at best. With the passing of Mr. Taddeo about 10 years ago and his company dissolved subsequently, the original Digital Antidote and the V2 hardware are no longer available. The Digital Antidote Plus (DAP) in the iTube is however a new take on the original concept and according to iFi, updated to be compatible to the latest and upcoming HD format of music.

So history asides, does the DAP work as advertised? Well, the first thing I did is to get some measurement off. RMAA is really not great on measuring beyond the basic stuff and certain not for phase - but one thing to look for is the treble roll-off that inheres from the original Digital Antidote circuit. As you can see from the graph, the area around 8kHz is actually bumped up by 0.4dB, then it drops off to -1dB around 15kHz before ending up at -2.5dB @ 20kHz. Given human is only sensitive to about 1dB of SPL change, the actual effect will be more noticeable above 15kHz. But since most human, especially adult, have likely lost a significant amount of hearing on the high treble region, the actual impact on listening should be relatively small. In real listening, my 30+ years-old ears really didn’t detect any major loss of treble from album to album. One thing I do pick up, and in a very obvious fashion, is the increase of texture and detail in the mid to bass range. This is most noticeable when I was listening to Piano Guys’ first and second album, where the decay and body of the piano and cello becoming unusually clear and their timbre becoming almost too good. To use the TV analogy again, it will be the equivalent of switching from HD to a 4K signal - Okay, perhaps this all seems to be too much of a hype. But it really isn’t about how SD to HD, or how HD to 4K that matters. It is about the increase of overall information from one to the other. With the iTube alone, it is like filling the background with all the missing notes. With the DAP engaged, it is like those notes are brought to the foreground. Is that how ‘analog sound’ should be, or is it a better approximation of live music that is somehow lost in the recording process in the digital era? I truly have no answer. But I can say I don’t dislike it. It is something that I can leave it on all the time and don’t feel like it has degraded the sound in any way. In fact, I think the result is really a plus to the overall music listening experience – regardless of whether it is an EQ, a phase correction or just another technological voodoo.

One last thing to note is that I can pick up the difference on DAP easier on the headphones than on the speaker. Then again, my headphones are generally better sounding and more revealing than my speaker. Your mileage however might differ.



…in Conclusion
I have a very small computer desk that also doubles as my working and listening area, and it is constantly full of all kind of gears and never enough in space. Early last week after receiving the iTube, I had the whole iFi chain setup on the desk for the iTube review and thought that I would have to disassemble them quickly in the next few days in order to reclaim the space back. The whole setup, as I am about to finish writing this review, is still sitting on the desk after almost 2 weeks. It could very well be staying there for a while longer, given how much music I have been enjoying recently over my Creative speaker - and to think that I am predominately an on-the-go IEM user. I guess this really sum up the iTube magic thingy. Sometime it is the seamlessly little stuffs that add up to make the whole experience worthwhile.

A thank to iFi Audio for the review sample

 
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Disclaimer: A big thank you to Ifi for loaning me the iTube for this review!
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After hearing the iCan I was eager to get my hands on more Ifi gear. Now I've even been lucky enough to get almost their entire catalog, as well as an exclusive. The iTube is launched today - 16th August (£275). This is a fascinating little audio gadget - a buffer stage with a pure analogue circuit that includes an active tube (GE5670). The iTube can be added to pretty much any audio chain with a dedicated amplifier (before the amplification stage), be it for headphones or speakers. Additional features include the option to boost sound by 6dB, it can be used as a pre-amp (with or without the 6dB boost), but it also has two other features to modify sound. One is called '3D Holographic' - a three position switch that alters soundstage for different systems, correcting for frequency definition and speaker placement. This was first seen on the iCAN, although that one was tuned for headphones and this one is tuned purely for speakers. To help me explain the second feature [the Digital Antidote] here's some info from Ifi:[/size]
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"The original patented Digital Antidote circuit takes the analogue input signal and executes various timing and phase correction duties, all in the analogue domain. This drastically reduces phase error introduced by the digital source as well as increasing the amplitude resolution (by nearly one bit). Yes, there is a small roll-off effect but as one can see, it certainly is not a simple roll-off filter.[/size]
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[size=medium] With the iTUBE’s Digital Antidote Plus®, this active tube [version  3.0] is ready for all digital formats right the way up to the latest high-resolution PCM/DXD/DSD and beyond. Now you can finally relax and enjoy your digital audio for longer."

The 'Digital Antidote' (which I will refer to as 'DA' from now on) can be turned on or off with a switch on the front of the unit. At first I thought that this switch might act as some kind of bypass for the entire system, removing the tube from the chain, but this is not the case (the tube is always being used). It's nice that you can add the DA effect on top of the tube buffer, this just meant there was no easy way for me to A/B the effect of the tube itself.[/size]
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I admit to having no experience with tube amplifiers thus far (of which I'm quite ashamed), but I am very keen to hear some. The potential with the iTube is pretty clear, benefits of tube sound while keeping your solid state amplifier - an interesting prospect indeed. Here's a close-up shot of the glowing tube (this thing does get hot!), viewed through the dot of the 'i' in the company logo - nice design touch guys.[/size]
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[size=medium]      SOUND[/size]
[size=medium] I was expecting a tonality shift with the iTube added to the audio chain. I assumed there would be more warmth, stereo-typically associated with tube amplifiers, but no. I've heard of some tube amps defying this preconception, but perhaps this is more to do with the tube not being in the amplification. For those interested in the iTube who are still fond of their Solid State amplifier's tonality, you'll be happy to hear that there's little change in this regard. The caveat is that some instruments feel inherently different in their presentation. They sound better rendered, more full and perhaps this leads to them sounding a little "warmer", but I felt that there was no overall colouration. Certain aspects of the sound just seemed more real/natural. A nice smoothness is infused to the sound, which I noticed and enjoyed more the more I listened.[/size]
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The changes that the iTube brings can feel subtle initially. This is not true of the 3D holographic sound however, which was very obvious and easy to A/B. Unfortunately A/B'ing the rest of the effects is impossible to do with ease due to a slow switching process of the iTube from the chain. Unless you have an identical system (source, amplifier and speakers or headphones) it's easy to forget the exact sound you were listening to. After getting used to the iTube being in the system however the music felt instantly more jarring (harsh and edgy) once the iTube was removed. Then all I wanted to do was put the iTube back in. [/size]
[size=medium] The same thing happened to me when I first started listening to expensive systems. Going up I didn't notice much, but coming back down it really hit me. Like a computer upgrade you seem to adapt and accept improvements with little perceivable difference, whereas a downgrade is very different story. Over time it feels like my brain has picked up these differences in general, but when you're not used to something it can easily go unnoticed.[/size]
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The DA effect is a tricky one to pin down. Although it should be easy to A/B because of the switch, I struggled to tell the difference between it being on or off. It's a more subtle effect than the tubes but perhaps I'm still in my early stages with this one. Ifi explained to me that it makes a bigger difference in lesser systems. I didn't spend a huge amount of time A/B'ing this effect unfortunate as I was mostly switching it between speakers and headphone systems. I usually had the switch on when it was being used so if that added to the effects it had on my system then I'm glad it's there. [/size]
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[size=medium] The 3D Holographic Sound in the iTube has been redesigned to cater for different speaker positions so is quite different from the version found in the iCAN. The effect in the iTube seems rather more subtle than the iCAN when used with headphones and I did enjoy it at times, but I'm told that it's not designed to work like this. [/size]
[size=medium] For speakers this is a really nice feature to have considering that they are often fundamentally difficult to position and tune for the best soundstage. My speakers are a little cramped for my living room and they really benefited from the wide effect on some tracks. I also liked being able to change it for different music, so a big thumbs up from me here![/size]
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[size=medium]      COMPARISONS[/size]
[size=medium] There are a few tube buffers around already, but it's certainly not a common consumer product at the moment. There's the Musical Fidelity X10 V3 (discontinued, but sold for around £250) and the Grant Fidelity B-283 (around £150). Searching for a 'tube buffer' on Google mostly brings up eBay listing from China. Unfortunately I can't say anything about how the iTube compares to any of these other models on sonic ability. What I can say is that the iTube seems smaller and neater than the consumer models mentioned above. Some of the eBay tat looked equally sized, but not exactly neat or pretty (exposed PCB's and bits sticking out).[/size]
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I found an interesting paragraph on the Grant Fidelity website titled "who the B-283 is not for". It points out that if you've already spent a lot of money on your audio set up ($10k+) then you won't hear much of a difference by adding a tube buffer. Their reasoning is that you would have already paid good money to provide the same effects that the tube buffer provides. Having heard the £3500 Resonessence Invicta's wonderfully smooth sound I can say that this sounds like a very reasonable statement. That said, I feel the need to point out the iTube's additional features for controlling harshness and soundstage and what they could also bring to a system. [/size]
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[size=medium]      BUILD[/size]
[size=medium] The construction of the iTube is pretty good. It's all solid metal on the outside, even the volume dial. It comes complete with rubber feet, power extension and two sets of RCA leads to get you started. The shape and style is also consistent with the rest of the Ifi range so if you would like to combine them they do stack nicely. I have almost the entire range of Ifi gear here at the moment and can say that not only do they stack nicely, but they sound great together too. The max combination you can utilise in one go consists of five devices!:[/size]
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[size=medium] Computer > iUSB > Gemini > iDAC > iTube > iCAN > Headphones - wow![/size]
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That's a pretty impressive collection of devices to make sound, but what a beautiful sounding system it is. Although visually it could do with some smaller and prettier RCA cables it's quite pretty too. [/size]
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[size=medium] Also required to connect these monsters are: another USB cable, three power leads and two RCA cables. All of this is supplied of course, but it won't look quite as neat as this when it's working. My only real complaint about this setup is that you can't output all that to speakers at the same time as headphones. Before I get too deep into analyzing these units as a whole, let's get back to the iTube...[/size]
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The power switch for the iTube is built into the metal volume dial. If you're not using the unit as a pre-amplifier as well then you can turn it anywhere to the right to turn it on. When you do you will see the green lights on the front come on and the tube will start glowing. I wish that the iCan had this same mechanism. The only way to turn that off is to yank the power cord out, which is less than ideal on a class-a amp that gets almost as hot as the iTube.[/size]
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The iTube is a pretty simple and straight forward device, with no real down sides. If you turn on the iTube before the amplification you can get a loud popping noise, but this is true of pretty much any source to some extent and should always be avoided anyway. I made the mistake once, but never again. I can't even nit pick with the heat since that's simply the chassis doing a good job at heat dissipation. I'm really scratching my head to think of negatives at this point... no, there really isn't anything to speak of.[/size]
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[size=medium] Moving around the iTube is something you might do often if you switch it from a headphone to a speaker system, like I did. I did wish for dual outputs on the iTube so that it could be used for both system more easily, although that would force the chassis to be larger, since there's no room for another set of RCA outputs. I'm not sure that would have a desirable effect on the circuitry either, so the only option will be to have two of them.[/size]
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     FINAL WORDS[/size]
[size=medium] I'm not quite sure what I expected from the iTube, because it did surprise me in a few ways. Initially I felt a little let down by it's subtlety, but ultimately I came to appreciate that subtlety rather a lot. I like that it doesn't change the tonality of your amplifier and the smoothness it adds to the sound is addictive - it does what it sets out to.[/size]
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I expected to notice the effects and appreciate the iTube more with headphones, but so far it's the speaker system that has impressed me the most (with the 3D effects too). I'm not saying that it doesn't work with headphones, because I don't want to live without the iTube in either of my systems.[/size]
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[size=medium]      EQUIPMENT USED[/size]
[size=medium] Desktop PC, Media PC, Dell Vosto Laptop, Ifi iCan, Ifi Gemini, Ifi iDAC, Ifi iPower, Audiolab M-DAC, Audiolab 8200P, Denon AH-D7000, Hifiman HE-500, SoundMAGIC HP200, WeSC Chambers RZA Premium, Epiphany Acoustics Atratus, Schiit PYST, Arcam rBlink, Samsung Galaxy Note 2[/size]