iFi Micro iTube2 Vacuum Tube Buffer and Preamplifier

General Information

Reloaded, next generation! The original iTube became the 'go to' tube buffer for any and every home audio system. The iTube2, with trickle-down from the flagship 'Pro' series, has been redesigned with new parts and new circuitry. Only the GE5670 tube remains. The iTube2 is a tubed output stage; tube preamp; tube buffer and an impedance-matching device. There is nothing like it. Put the iTube2 before a solid-state preamp with another iTube2 after it, creating the effect of tubing the whole audio chain. Or simply use the iTube2 as a very high-quality preamp by itself. The iTube2 sounds by and far like a tube amplifier 'done right with the inimitable magic of tubes'. Tube+ circuit for SET/Push-Pull/Classic tube amplifier signature2. 3D Holographic+ for Loudspeakers matrix system3. XBass+ for Loudspeakers matrix system.
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Pros: + Sound Quality
+ Special Effects
+ Tube performance is quite good
+ Good build quality
Cons: - iTube2 gets pretty hot during usage
- iTube2 works better for a speaker setup than it works for a headphone setup
Power of Change - iFi iTube2 // iPower // DC iPurifier 2 - Review



iFi iTube 2 is a preamplifier priced at 400 USD, and comes to enhance your home listening experience. If your setup doesn't have a good quality power brick, you can always go for iPower from iFi, which is priced at 50 USD, and if you're looking for something to filter the power coming from your power brick, the iFi DC iPurifier 2 can be had for about 100 USD




Introduction


iFi iTube2 is a Tube PRE-AMP designed for large home systems, while iPower is a power converter that comes in handy if your source doesn't come with a quality power brick, or if you need a replacement power brick. There will also be a bonus product features in this review, the DC iPurifier 2. Since I have no comparisons for any of those products, I'll try comparing them with other options out there throughout the review, but there will be no special comparison section within the review.

It should be noted that I have absolutely no affiliation with iFi. I'd like to thank iFi for providing the sample for this review. This review reflects my personal experience with iFi iTube2, iFi DC iPurifier2, and iFi iPower. Every opinion expressed is mine and I stand by it, the purpose of this review is to help those interested in Wells Milo find their next music companion.



About me

https://www.audiophile-heaven.com/p/about.html



Packaging


First things first, let's get the packaging out of the way:











iFi's package is always over-the-top, and for everyone one of those accessories, you get a white box, and a LARGE selection of cables and connectors. To be honest, there's not much I could have imagined necessary for any of them, although if I was to call out something I wasn't entirely happy with, the RCA cables that come with iTube2 are a touch short, but for the amount of raw accessories included in the package, iFi is just golden and will set you for fun.

It should be noted that while the DC iPurifier works with any power brick, iPower has a precise power rating, and if you're replacing a power brick, you should make sure that you're getting the right power rating for your iPower.



What to look in when purchasing a high-end DAC/AMP


https://www.audiophile-heaven.com/p/what-to-lookl.html



Build Quality/Aesthetics/UI/Firmware


iFi iTube2

The physical description of iTube2 makes it look like something entirely different than what it actually is, as if you're used to iFi devices, judging by the shape and size, you'd expect it to be some kind of DAC/AMP, but actually it is a preamp or buffer that has a real Tube inside. The entire device has iFi's nice finish that doesn't get scratches and has that industrial / cool look, but since you're going to have this set up in a home system, I think that the scratch resistance isn't quite that relevant.








The device has three switches in the front, one for 3D+, one for XBass+, and one for Push-Pull / Single Ended / Classic Tube setting. There's also a large number of sliders beneath the device, which lets you select whether you're using iTube2 as a Buffer with a 0DB gain, or with a 9DB gain, or whether you want to use it as a Preamp with 0 or 9 dB gain. This comes in handy if you want to change the purpose of iTube2, and if you feel you need more volume in your system, or if you want to have a larger or finer volume adjustment from the volume wheel of iTube2.

Since if you're reading this review, you may be wondering whether you need iTube2 in your system, and you may be wondering what does it do exactly, basically, you connect it between your DAC and your Power Amplifier, and it acts as a sonic enhancer, and a Preamp / Buffer, basically enabling you to either have another volume control step, when used as a Preamp, or just adding some Tube Magic to your sound when you're using it as a buffer.

The tube inside iTube2 is a GE5670 Tube made by General Electric, one of the best Tubes in existence for its size and Type.






iFi boasts about their iTube2 having DirectDrive, which is basically a fancy way of saying that there are no output coupling capacitors, leaving the signal with less filtering and leaving as little coloring on the signal as possible, besides the magic that the Tube itself does, or, if you're feeling keen, the magic that the extra enhancements do (X-Bass and 3D Soundstage).

There's a couple things I would want to note after having used iTube2, the first being that it gets extremely hot, this has a real life tube inside, and all you've heard about tubes is correct, it runs so hot that you don't want to touch it after it warmed up. On this note, it is better to leave it to warm up a bit after you started it, as Tubes tend to sound best after a few minutes since they've been turned on.

iTube2 doesn't consume a lot of power, being rated at 4W in idle, and 10W at maximum, being rather power efficient and being one device that's not going to increase your power bill.



Another thing I noticed after using iTube2 for a while is that the effects, the X-Bass and 3D soundstage are both very tasteful, and well implemented, leading to a very nice overall tuning, they do what they're supposed to, but they don't overdo things.

Another thing I noticed is that iTube2 will work with some if not most Headphone Amplifiers, if you want to add a bit of Tube Magic to your Headphone setup.



iFi iPower


Here, things are far simpler, and there's very little to talk about, as iPower is basically a power brick. It is black in color, and it comes with a wide selection of connectors, including exotic ones, or a few that have reversed polarity, leading to a device that's quite versatile.



It is meant to be used as a power brick replacement, basically making sense if either your system has a poor power brick, or if you're curious if the power converter is throttling your sonic performance, or to be used if you burned a power brick and can't outsource the original one, or if you want to go with a good quality one instead.

iPower doesn't get hot, it doesn't have any glaring issues, nor does it have a lot of features, there are no switches, no options, pretty much it is something you plug in your power outlet and forget about, which is good, because this is how a good quality power brick should act.



iFi DC iPurifier 2

The DC iPurifier 2 is a pretty fancy thing, a power filtering mini device that does get a bit hot. Physically, it is a small rectangural-shaped accessory that has a white-ish color, and a small input and a small output.



The main idea behind it is that SMPS, or Switch Mode Power Supplies, the type of power brick most often employed in audio devices, weren't made for audio applications, and are actually quite noisy. This is actually a true scientific fact, but most companies consider that those power bricks are good enough for audio, and that you wouldn't hear a power conditioner.

The good part about iPurifier2 is that it works with basically anything, from DACs to AMPs to DAWs, so even if you're a music producer, it would make sense to get one. The power handling is from 5 to 24 volts, and from 1Hz all the way to 5 GHz, making it a very versatile device. The power rating is also up to 3.5A, 84W, so you don't have to worry even if your DAC/AMP/DAW pulls in quite a bit of power from the outlet.



Sound Quality


iFi iTube2

I need to start out by saying that I have been able to reliably compare iTube2 and what it does to sound, but I should also note that I noticed far larger differences when integrating iTube2 with a Speaker system, than when I used it with a headphone Amplifier. This is important, because it looks like most reviews that focused on using iTube2 to feed a headphone amplifier have told stories about minor improvements and small changes, while everyone who's been using it with a larger speaker system tells stories about larger changes.




I spent way more time with itube2 integrated within Speaker systems than I did with it integrated in a headphone chain.

Starting with the bass, iTube adds weight and depending on the setting, it adds some decay to each musical note. This can be felt quite easily, as you play with the different harmonic settings, and if you're a fan of adding more bass and sub-bass, you can engage the X-Bass feature, which now has two settings. Although one could call the 6dB setting moderate, adding 12 dB of bass at 20 Hz really increases the impact and the thickness of the sound.

The midrange is generally warm, thick and organic. This being said, it also feels a touch colored, at least on most of my test setups, and iTube2 seems to have a pretty strong color of its own, and instead of being transparent, it tends to employ its own signature in music. This being said, it has a rather wide soundstage, and if the soundstage at its original setting isn't enough for you, the 3D soundstage feature is quite effective, although besides increasing the soundstage width, that setting also increases the upper midrange / lower treble, and the final result is brighter, so if your system is already a bit bright, it won't be recommended to engage the 3D soundstage setting.



The treble of iTube2 is a touch on the smoother and warmer side, compared to the original sound, without introducing it. This plays well for older recordings, but kills some of the sparkle for Metal Music, and if you're into a smoother, simpler, leaner sound, you're set for fun, but if you were looking for a more energetic approach, then iTube2 probably will feel a touch recessed in the treble.

Now, there's one more thing to talk about, which is the texture of the sound, iTube2 doesn't necessarily sound like any other Tube AMP, but instead, it has a pretty specific coloring to textures, all of its Tube settings adding some delay to each musical note, and this becomes evident once you do some tests. This works well because it tends to make the entire sound larger, bigger, but also tends to smoothen the entire sound a bit, adding some dampening to everything. For a larger sound system, this works well to create a warmer, some realistic sound, especially when the speakers don't keep up with the music all that well, but for headphones the differences are smaller, and for really expensive systems, you may not want to increase the decay of each musical note, so the usage of iTube2 will be very system-specific and it will be up to you whether its unique signature works for you.



iFi iPower


iPower is basically a power converter that is a SMPS, so it does not state that it is a linear power supply, or an LPS, but it states that it improves on the sound of a SMPS so much that you can barely tell it isn't an LPS. On this note, I can't say I know how an LPS sounds like on any of the systems I tested iPower on. Most people seem to agree that iPower brings an improvement in Soundstage, Background noise, and Detail and Imaging. The main thinking behind this is that some of the details are covered by the background noise, so when engaging iPower, you don't have to worry about the background noise anymore, which will allow more details to be heard, make the soundstage wider / larger and add to the imaging.

The thing is, in most of my experiments, I haven't heard much of an improvement, or at least, not one I can correctly quantify. It sounds pretty much the same as the built-in Power Converter within Mytek Brooklyn DAC+. This doesn't mean anything bad, and if you're already using a pretty inexpensive device, you're going to have a much better sound with iPower, as it has the quality of the power delivery in a 2K USD DAC/AMP, but if you already have a flagship level device, iPower will most probably be a power converter replacement rather than an upgrade. There are other iFi products that may help you more, like, for example, their power strip.



iFi DC iPurifier 2


The DC iPurifier 2 is an upgrade from the original, at least in pricing, being more affordable than the original was. With iPurifier, it is a bit easier to tell the difference between having it and not having it in your system, and I think it is a worthwhile investment if you have a really expensive DAC or Headphone AMP, and if you want to make sure that it isn't getting any noise from the power converter, or rather, if you want to improve a bit on that area.



I've been able to discern a blacker background and a better overall definition with Young MK III DAC, along with a better overall background noise. This being said, whether it is worth the 100 USD investment is solely up to you and how much you price those small improvements, but if you're looking to squeeze every last drop of performance from your system, then the DC iPurifier should help a bit, especially with more revealing DACs or AMPs.



Desktop Usage

iTube2 is a pretty good-looking device and the most important aspect you'll probably wonder about its usage is whether it gets hot, and oh boy, does it get hot like the sun on a Sunny Day in July. This means that you shouldn't place it too close to other devices, and that you should mind it having enough space around to be able to ventilate. This isn't an issue, just an inherent detail about Tube AMPs in general.




DC iPurifier 2 is a really small device, and if you don't want it to pull on the motherboard or the power plug of your device, it comes with a little cable extender, so it can rest on the table, or next to the device. It tends to get a bit warm during usage, but nothing to worry about, and it can be safely used next to other devices.

iPower tends to be pretty much the ideal size for most power outlets, and it won't feel different from most power bricks. In fact, if anything, it is smaller than most power bricks, meaning that you can organize your overall setup to be a touch more tidy and to sit more comfortably. iFi also designed a larger power strip that would have enough space to accommodate even larger power bricks.



Pairing


I have paired the power brick, iPower with the M2Tech Young MK III DAC, iTube2 with a few setups, the most important being with the Taga Harmony 800 Series that I reviewed in the past, and I tried placing the DC iPurifier in multiple locations, and it always had pretty much the same effect.



iFi iPower + M2Tech Young MK III DAC - Young MK III is a really new and interesting DAC from the Italian Company M2Tech, and it makes the word go round if you love a large soundstage and a crisp sound, a very detailed and clear presentation, and if you love a neutral response from your dAC, and if you don't look for any coloration and enjoy transparent sounding devices. All I can honestly say about iPower is that due to its nature, a double blind test was physically impossible, so I can't guarantee the results with the same accuracy as I do for other reviews. Not only I don't have two DAC units, but it takes a while for the unit to start up, making the test a bit inaccurate. I can say that iPower sounds at least as good as the power brick that Young MK III comes with, and that changing the power brick didn't make the sound worse, and if my imagination isn't playing tricks on me, I could say that I heard some improvements in how black the background is, but that's pretty much as far as I would guarantee in terms of changes that adding iPower vs the original power brick does. This being said, the final resulting sound is very enjoyable, with a clear and natural tone, huge soundstage that just extends endlessly, and with a very quick and detailed bass.

iFi iTube 2 + Taga Harmony 800 Series Setup - Here, I have been able to set up iTube2 in such a way that a volume matched test was possible, so don't worry, here I did the tests, which were how does the system sound if I introduce or if I don't introduce iTube2. In all ways, the system sounds more organic, but also thicker with iTube2, but I've been able to play with the sound even more, using the 3D setting and the X-Bass setting, turning the whole system into a much more enjoyable one.

iFi DC iPurifier 2 + Burson PlayMate - Burson Playmate is quite a badass DAC/AMP that has a full Class-A power deliver, and consumes quite a bit of power. Although proper blind tests were not possible, I can describe more differences here than when I added iPower to a setup, it feels like the DC iPurifier does make the background more black, resulting in more background instruments being audible, and in the soundstage feeling a tad larger. This being said, the tests could not have been conducted with proper volume matching, so take this with a grain of salt. The differences were mostly audible at high volumes.



Comparisons



iFi iTube2 vs Feliks Echo Tube Amplifier - I decided to go ahead and include this comparison to show how a 500 USD Tube Amplifier compares to iTube2. Feliks Echo is an OTL Tube Amplifier, which means that it was designed for higher impedance headphones, but as I tested in my review, it will work plenty well with lower impedance headphones as well, and even with some IEMs. For just 100 USD more than the price of iTube2, you get a device that relies on 4 Tubes in total, has a much larger and meatier power deliver, and which doesn't act just as a Preamp, but also as a Headphone Amplifier, so you may be wondering what does iTube2 have to say for itself. Well, iFi relies a lot on their configurable sound and tricky enhancements, and it plays well to their side, if you want a little Bass Boost, like the one found on iTube2, or if you want a little treble and space boost, like the 3D Boost option, both things which a classical OTL Amplifier doesn't have. Furthermore, you can configure the harmonics of iTube2 to sound like a Classic Tube Amplifier, like a Single Ended Triode, or like a Push-Pull configuration. This being said, if you're not a fan of tweaking, and just want a tube amplifier or a tube preamp, Feliks Echo tends to be cleaner and have a more even response, where iTube2 tends to thicken the sound more and have a more fun tuning, where Feliks Echo just adds the organic and sweet midrange specific to tubes to the sound, without taking much away from the treble or coloring the sound, being what I'd call more transparent.



Value and Conclusion


Every one of those little accessories will cost you a little penny, but iTube2 is actually a bit more than a little penny, as it is about 400 USD, making it a pretty considerably investment. This means that you should consider whether you want it in your system, depending on what other components you have, and on whether you feel that you want to add the Tube Sound magic described, if you need a Preamp, or if you are going to be using the 3D and XBass enhancements. Overall, though, all of them are priced fairly well for their purpose, and regardless whether you're replacing a power brick and you want a good quality one, if you want to filter the noise from your SMPS, or if you want to add some Tube to your already existent system, without investing in something larger or more expensive, then you're set for fun.



The package from iFi is always all-inclusive and you won't feel like you're missing something, and actually, you may find a lot of accessories you don't need right away, but which you may eventually need in your setup, so I always respect and admire when a company goes the extra step to include everything you may require with their products.

The build quality, regardless of whether we're talking about the iTube2, DC iPurifier2, or iPower, is excellent, and all of those devices are solid, made well, and will work really well for a long time. All of them have their own usage scenario, but only iTube2 has a bit you can talk about, like the sonic enhancements found in the form of 3D Soundstage, and in the form of X-Bass. You can also configure iTube2 to act as either a Preamp or a Buffer, and you can give it a little volume boost if you feel you need it, although I feel that for most systems the power boost will stay at 9dB, as it allows for a more granular volume control.



Overall, if you're looking for a nice Tube Pre/Buffer, that also has high-quality analogue sound enhancements implemented, iTube 2 makes is one of the best options out there. If you're looking to replace your power brick, then iPower surely is a high quality power brick, and regardless of whether you'll hear a sonic improvement or not, when you have a high-quality DAC like the M2 Tech Young MK III, you will surely want to have the best power converter available connected to it. If you want to make sure that you filter all of the noise from your SMPS, then getting the DC iPurifier2 is an excellent option, and much cheaper than getting some of the more fancy power filters, despite doing a really good job itself.



Full Playlist used for this review


While we listened to considerably more songs than those named in this playlist, those are excellent for identifying certain aspects of the sound, like PRaT, Texturization, Detail, Resolution, Dynamics, Impact, and overall tonality. We recommend trying most of the songs from this playlist, especially if you're searching for new most, most of them being rather catchy.



Youtube Playlist


https://www.youtube.com/playlist?list=PL_cjBXGmwSHSdGcwuc_bKbBDGHL4QvYBu



Tidal Playlist


https://listen.tidal.com/playlist/64555551-ec3c-4279-ae44-248fdfcf6c4b



Song List

Bats - Gamma Ray Burst: Second Date

Eskimo Callboy - Frances
Incubus - Summer Romance
Electric Six - Dager! High Voltage
Kishida Cult - High School Of The Dead
Dimmu Borgir - Dimmu Borgir
Breaking Benjamin - I Will Not Bow
Thousand Foot Krutch - The Flame In All Of Us
Gorillaz - Feel Good Inc.
Infected Mushroom - Song Pong
Attack Attack - Kissed A Girl
Doctor P - Bulletproof
Maximum The Hormone - Rock n Roll Chainsaw
Rob Zombie - Werewolf, Baby!
Escape The Fate - Gorgeous Nightmare
SOAD - Chop Suey
Ken Ashcorp - Absolute Territory
Machinae Supremacy - Need For Steve
Ozzy Osbourne - I Don't Wanna Stop
Crow'sclaw - Loudness War
Eminem - Rap God
Stromae - Humain À L'eau
Sonata Arctica - My Selene
Justin Timberlake - Sexy Back
Metallica - Fuel
Veil Of Maya - Unbreakable
Masa Works - Golden Japang
REOL - Luvoratorrrrry
Dope - Addiction
Korn - Word Up!
Papa Roach - ... To be Loved
Fever The Ghost - Source
Fall Out Boy - Immortals
Green Day - Know The Enemy
Mindless Self Indulgence - London Bridge
A static Lullaby - Toxic
Royal Republic - Addictive
Astronautalis - The River, The Woods
We Came As Romans - My Love
Skillet - What I Believe
Man With A Mission - Smells Like Teen Spirit
Yasuda Rei - Mirror
Mojo Juju - Must Be Desire
Falling Up - Falling In Love
Manafest - Retro Love
Rodrigo Y Grabriela - Paris
Zomboy - Lights Out
Muse - Resistance
T.A.T.U & Rammstein - Mosaku
Grey Daze - Anything, Anything
Katy Perry - Who Am I Living For
Maroon 5 - Lucky Strike
Machinae Supremacy - Killer Instinct
Pendulum - Propane Nightmares
Sirenia - Lithium And A Lover
Saving Abel - Addicted
Hollywood Undead - Levitate
The Offspring - Special Delivery
Escape The Fate - Smooth
Samsara Blues Experiment - One With The Universe
Dope - Rebel Yell
Crazy Town - Butterfly
Silverstein - My Heroine
Memphis May Fire - Not Over Yet


I hope my review is helpful to you!

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Contact me!











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Pros: Depends on the system, but for me is a great add-on that gives my music a more human and magical presentation.
Cons: I have none
I have a real problem with ifi ITube, and is that when it goes out from the sound I really miss is magic it does, the brain misses the natural presentation and body that the iTube gives to the sound.

With the iTube in the middle ou the audio chain the presentation and soundstage is more human and the overall result is longer audio sessions without fatigue.

This is something you notice immediately when you take it out, the body and the magic it does simply vanish, so you can’t live without it, that’s the effect of valves.

So for sometime now I was planning listening the the iTube 2, the one in the photos, and… It’s an evolution, it appears small saying this way but believe me it’s an enormous evolution from the original, I do not know how ifi pulls it out, but they impress me with every itineration of their micro line, it start’s where the original iTube made to the sound and everything is more transparent, detailed, warmer if you desire.

And the switches, this time we have better and more to explore, you can up the bass to 6db if you have speakers that can go only to 40Hz, or 12bd for speakers that only go to 80Hz, or you can go totally crazy and go in big speakers and up the bass, your house will be full of bass notes, I have made this in Stanley Clarke At the Movies album and the bass that the solo 6be produced made my room almost break.

The iTube 2 also have a new better 3d implementation, as I listen on my desktop I have used it on some tracks, and the new implementation is much better than the original iTube, as this is a question of personal preference and in some cases it’s an effect I like, and use it in classical, ambient or new age, it’s grows on you. For me this one turns some albums in magical one, and a new way of experimenting them.

So this iTube 2 iteration is a go for me, it’s difficult when you have such an upgrade like this in your audio to have to go back, and I do not want to go back, this will stay.

Attachments

Pros: It brought the magic back to my music!
Cons: Absolutely nothing!
frontGlass.jpg

Intro


iFi is a brand born from trickle-down technology, licensed from AMR with one simple mission: To provide the absolute best quality ‘Bit-Perfect’ audio from computer generated sources . All iFi products proudly boast clean Class A analogue circuitry with absolutely no digital signal processing; The signal stays true to the source throughout! Since iFi broke into the scene in 2012 they have been making huge waves in the audiophile community, offering products who’s performance is on par with their beautiful, modular design! Every product has been carefully engineered for perfect symmetry and synergy with one another, allowing the user to custom tailor their stacks to their desired needs.

As part of the original micro line, the micro iTube was an incredibly popular product. Described as the ‘Swiss Army Knife’ of components, the original micro iTube boasted a tube buffer (0dB or 6dB gain), pre-amp with analogue volume control (0dB or 6dB gain), 3D enhancement effects for speakers, as well as ‘Digital Antidote Plus’, a feature designed to take the “digital’ out of the source and make it sound more ‘analogue’. For many, the sleek and sexy multi-functional micro iTube was hailed as something they never knew they wanted, let alone needed! Building upon it’s success, iFi audio took everything that made the micro iTube great and started over, keeping only the NOS GE 5670 tube! Heavily influenced by their flagship product, the iCAN Pro, built from the ground up using trickle-down technology the micro iTube2 was born!

Disclaimer/Acknowledgement

The micro iTube2 was sent to me on loan direct from iFi Audio USA in exchange for my impressions and review. The words I write are my own and are honest, objective, and free of bias. I received no financial compensation for my effort, only the satisfaction of trying out a quality product for a few weeks.

More importantly, I would like to thank Lawrance over at iFi Audio for providing me the opportunity to review the micro iTube2. Out of the blue I was sent a message here at Head-Fi asking me if I would like to spend some time with their newly released micro iTube2! As a proud owner of iFi products, how could I say no? However, due to popular demand and higher than expected sales by the time our e-mails had crossed back and forth, there were no units left to send out! No worries as I was asked if there was another product that I would be interested in trying out until the inventory levels for the micro iTube2 had been refreshed. How awesome was that? I chose the iPurifier2, and if your would like to read what I thought of the device, click here. So anyway, a short time later a review unit was ready to be shipped out, and here we are today, micro iTube2 in hand. You know what they say, “ All good things come to those who wait. “… or perhaps “ Shut up and take my money! “ might be better suited in this case!

About Me

Born in 1978, I grew up in a family consisting of musicians, broadcaster/sound engineers, and amateur DJs. I always had a deep appreciation and understanding of both music and sound. I was further educated in this self interest after taking courses in both basic electronics and Sound: Electro-Acousto - The Path to Golden Ears. While I believe a listener’s preference in sound is subjective, the science behind it is not. I am not swayed by buzzwords, hype, trends, brand recognition, or big numbers on charts. Opinionated as I am, my words are not only objective but honest. I view all criticism as constructive, as long as it is sincere.

Specifications

Tube: N.O.S. G.E. 5670
Maximum output: > 7.75V (>+20dBu)
SNR: 119dB(A) re. 2V, buffer, 0dB Gain
DNR: 131dB(A) re. +20dBu, buffer, 0dB Gain
THD & N: < 0.009% (re. 2V, buffer, 0dB Gain, A- weighted)
Frequency Response: < 10Hz -to > 200kHz (-1dB) 20Hz – 20kHz (+/-0.003dB)
Input impedance: 1M ohm Direct Tube Buffer 100k ohm Pre-Amplifier with Volume Control
Output stage output impedance: <1 ohm
Corrected output impedance: <150 ohm
Input voltage: AC 100-240V, 50/60Hz
Power consumption: <4W idle, 10W max
Dimensions: 175(l) x 67 (w) x 28 (h) mm
Weight: 278g (0.61lbs)

Features

- Anodized in ‘titanium’
- Analogue Volume Control
- iPower (15V)
- 3D Holographic+ matrix for speakers (off/3D+ width/3D+ 30°)
- XBass+ for speakers (off/6dB 20Hz/12dB 20Hz)
- Tube+ (SET/Classic/Push-Pull)
- Tube buffer (0dB/9dB gain)
- Tube Preamp (0dB/9dB gain)

Brand-new PCB, Direct-Coupled for purest signal path

The iTube2, in-line with the latest iFi products, is ‘Direct-Coupled.’ This means no output coupling capacitor for the purest, most direct signal path.

iTube2.png

Reference class parts quality

The iTube2 employs Japan TDK C0G type capacitors. These are complimented by Japan Panasonic ECPU Film Capacitors explicitly designed for audio use with extremely low distortion (<0.00001% @ 1V/10kHz).

The iTube 2 also uses ELNA SIlmic capacitors. These and other parts are only found in components with an extra ‘0’ to the price.

The proof is in the listening. The best tube buffer/pre-amp out there just pulled even further ahead.

‘Magic’ of SET, Push-Pull or Classic Tube sound

In the ‘magic of tubes’ listening stakes, the iTube2 offers the listener the choice of different key sonic signatures:

– a Single-Ended Triode power amplifier;
– a classic tube amplifier.
– a Push-Pull tube power amplifier;


Just to note from the iFi team – there is no ‘right’ setting. We advise you to set according to your systems synergy and your listening preferences.

XBass+® matrix for Speakers

XBass+® for Speakers is quite different to its sister technology XBass+® for Headphones. The only similarity is in philosophy as the ability to enhance your Speaker listening is quite different to enhancing Headphone listening.

The former gives each and every audio system adjustable levels of bass control to enhance listening enjoyment through speakers that have limited bass extension. We have taken great care to ensure no degradation in sound quality occurs.

20 Hz (6dB): For speakers missing only the lowest bass notes (below 40Hz).
20 Hz(12dB): For speakers missing some bass notes (below 80Hz).
OFF: XBass+ switched out

3D Holographic+® matrix for Speakers

The latest 3D Holographic+ matrix for Speakers offers something quite special. It takes high-end systems to another level of performance. It was drawn from the original ground-breaking work of Alan Blumlein, the ‘father of stereo.’

Firstly, it corrects the fundamental spatial distortion in recordings. And secondly, it increases the width of the soundstage beyond that of the speaker placement.

30˚+ : This matrix adds an extra 30˚ to redress the narrow placement of speakers (eg either side of a PC monitor).
+ : This matrix recreates original ‘width’ of the soundstage and is the recommended DEFAULT setting.
Off : 3D+ switched out.

Accessories


iFi includes everything that is needed; High quality RCA interconnects (+1 for being purple!), an L-adaptor for the iPower to keep the connection flush against the unit, a handy super tiny flathead screw-driver to adjust the DIP switches in the event one’s fingers are unable to toggle them manually, a pad of rubber stick on feet, specification and warranty cards, and for good measures an anti-moisture pack.

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Packing

I am a huge fan of minimalistic yet functional packaging that gives the consumer the sense that they have purchased a quality product, and the iPurifier checks off all boxes on the list. Much like iFi’s other products, the iTube 2 comes in a white, almost Apple-esque sturdy box made of 100% recycled materials free of any toxins that meet environmental standards. The device is nestled in a sturdy cardboard tray with the accessories neatly packaged in compartment underneath; There is no wasted space holding nothing but air, rather only what is needed. A big ‘“hats-off” to iFi for thinking of more than just their bottom-line!

Build/Design

Measuring 158 x 68 x 28mm and constructed of recycled CNC aluminum, from a build and design perspective the micro iTube2 is purposefully identical to the rest of iFi’s micro line. Every component of the micro line are designed to be stacked with one another so consistency and conformity is a must for both logistics as well as aesthetics. Like it’s line-mates, the micro iTube2’s anodized shell is titanium in colour (albeit a slightly darker shade) with identical body lines and curves. The front and back plates are held together with 4 small screws and adds a nice utilitarian look without being too cluttered or gaudy in relation to the controls.

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Growing up in the 1980’s I am very familiar with analogue volume potentiometer and toggle switches. Rarely have I encountered a more smooth, solid, and balanced pot as I have on the micro iTube2. Saying that the volume pot is of high quality is an understatement as it not only possess perfectly smooth rotary tension, to my ears there is virtually zero channel imbalance when turned to the lower quarter of the dial! The recessed chromed toggle switches are of equal quality, and possess a smooth yet tactile rigidity. The toggle action is solid; Moving the switches up and down was easily done with absolutely no wiggle or play detected while in action or in place! Without a doubt, much like every one of iFi’s products, the micro iTube 2 is a quality product that is built to last!

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The text on the micro iTube2, both on the faceplate as well as the underside, was easily discernible despite being essentially grey-on-grey. Whether the environmental lighting was akin to a man-cave, recording studio, living room during high-noon, or simply nothing more than the LEDs of a computer monitor, no matter the situation I never had readjust my viewing angle to read what operation I was trying to achieve. This can not be said about iFi’s previous generation and even more recent products. From my own observations, the darker titanium anodized coating and the darker colour of the graphics give both a better contrast under a wide range of lighting as well as helps alleviate the reflection across the surfaces. Owning the original micro iDAC (mid 2012) as well as the recently released micro iCAN SE (late 2015), I can tell you first hand that the new colouration is a welcome change.

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Pre-Amp and Buffer

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While loaded with a plethora of features, the micro iTube2’s basic functionality can be summed up as either a pre-amplifier or a buffer (SET filter). So what is the difference and which should you choose to use for your set-up? Before I answer some basic understanding of why a pre-amplifier is needed. In an audio system the input circuit is the electrical audio signal recorded on media or running in from a microphone or pick-up. Its load is modifying the output circuit and applies a varying resistance to the output circuit to re-create the voltage fluctuations of the original audio signal. In most amplifiers, this load is too much work for the original audio signal. For this reason, the signal is first boosted by a pre-amplifier, which sends a stronger output signal to the power amplifier. The pre-amplifier works the same basic way as the amplifier in that the input circuit applies varying resistance to an output circuit generated by the power supply.

A good preamp is like Lingerie. It makes the content and playback more revealing, allowing the man a deeper insight into the source material, and paints a vivid seductive picture of the artists original intent, and keeps him thirsting for more... A good preamp titillates the listeners senses!

I hope this post explains things as it really matters, in a format more understandable to the lay audience than all the previous needlessly technical and geeky explanations.

--G0bble

- It can boost a low signal when your source and destination are far away from each other. A pre-amp can be beneficial in minimizing the noise that is picked up on the line to the power amp.
- It can clean up the signal. If you were going to be performing some filtering on a signal (i.e. a vacuum tube), the filtering elements can add noise to your system and by adding a preamp the noise is minimized compared to the signal.
- It can adjust the signal. Power amps can be more difficult to directly change the volume on while a preamp is much easier. So you can change your volume on the preamp and have a fixed gain on the power amp.
- It can act as a simple buffer between your source and the filtering equipment.
- Impedance matching. In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize or minimize signal reflection from the load. In other words, it takes the signal and optimizes it for the receiver.

Now that we have a basic understanding and uses of a pre-amplifier defined, why use the micro iTube2 as a buffer? Simply put, the buffer has fixed output and the pre-amplifier has variable output; It all comes down to one’s specific application and whether or not the volume pot is needed. If you have no use for a pre-amplifier and simply want to add in the magic of class-A SET into your system while implementing 3D Matrix and XBass, you would want to use the micro iTube2 as a buffer. If any of the above uses of a pre-amplifier is applicable to you, using the micro iTube2 as such is the way to go.

Break-in Period

While there is no mention of a break-in period in any of iFi’s documentation, the recommended industry standard for electrical devices and components is 40 hours. Personally, while I do tend to wait until 48 hours of real word use before making any written impressions, it is done not so much to listen for any changes in the sound rather to make sure the device and it’s components are operating correctly. From my own experience in both my home life and profession, if any issues arise they are usually detected early in the device’s life. Much like with the micro iDAC and iCAN SE, the 48 hour break-in period with the micro iTube2 yielded absolutely no change in sound, nor did I encounter any perceived problems or issues, a sign of a well engineered and constructed product!

Tube Warm-up

Don’t expect to turn the knob and immediately start jamming out to your tunes. Due to the nature of the tube itself, a warm-up period is required when the micro iTube2 is first powered on. Essentially, the inner workings of the tube has to reach an operating temperature before any sound could be heard. This time will vary depending on the ambient temperature, but it is not long at all. From my experience, the micro iTube2 will reach the optimum temperature in about 1 minute, give or take. Once fully heated, the device itself will get warm to the touch. This is normal and in no way will harm the device nor the components near by; The aluminium shell does a great job at absorbing and dissipating the heat evenly.

Initial Impressions and General Thoughts

Being old enough to remember the transition from analogue to digital, I had a longing to hear my music without the edge and sharpness created by todays digital equipment as I once did. A few summers past I went on a journey of (re)discovery and purchased several tube buffer/pre-amps from eBay ranging in price between $50 and $200 CND as well as every type of compatible NOS tubes I could get my hand on (including the GE 5670 JAN, my favourite). It was no co-incidence that at the time I had been reading up on the original micro iTube with an end goal of bringing life back to my digital recordings. My experience could only be described as lacklustre. Given the absence of such devices in my signature and profile, as well as my lack of postings here at Head-Fi, it goes to show just how much I truly though of the cheap Chinese tube kits. While they all worked as advertised, each underperformed. In terms of tube buffers/pre-amps most suffered from some form of clipping, attenuation, distortion, and noise. Sure, they did smooth things over and there was some fun to be had with shaping the sound, however in regards to the “tube magic”, there was none. While I did get a flavour of each specific tube(s) I rolled, the sonic effects could be better emulated using AU/VST plug-ins and a quality amp. Then there was the cheap components used and the sub-par construction… Needless to say by Christmas of that year all were sold, and I went back to drooling over the micro iTube.

A lot has changed in terms of my equipment between then and now, most notably my switch from the likes of Teac UD-H01, Audioengine D1, and SoundBlaster E3 to an exclusive iFi stack. My search for a smooth and detailed analogue sound was pretty much over as I was more than content with micro iCAN SE/DAC combo. After my experience with less than great tube buffers/amps and experiencing the class-A TubeState technology found in the updated micro iCAN SE (amongst others), I had come to the conclusion that a device such as the micro iTube2 wouldn’t be beneficial to my set-up, and if anything detract from the overall transparency through tube distortion. I couldn’t have been more wrong! Once integrated into the chain, it took but one song for me to realize that the micro iTube2 was more than a well engineered class-A SET pre-amplifier and tube buffer, it was magic!

The micro iTube2 came shipped with default setting of 9dB: pre-amp mode, and while that would be the eventual setting I would leave it set to, initially I changed it to 0dB: buffer mode as I was mostly going to be testing the unit in my iFi stack and headphones. Wearing my PSB M4U 1, the very first thing I noticed was the perfectly black background, and I do not mean it simply did not introduce any background noise, no, I mean it crated a vacuum like silence free of any discernible noise! I honestly thought the tube had not heated up enough and therefore I simply was not hearing the noise, yet. 10 minutes passed and at idle I still was hearing absolutely nothing! Switching the buffer and pre-amp gain to 9dB yielded impressively similar results. I used my PSBs for this test as they provide the absolute best seal I have encountered in a headphone and thus allows me to hear, if present, any garbage coming down the chain, and I encountered nothing of the sort. Even with both my BA and dynamic driver IEMs, at 9dB gain and maxed out volume of the micro iCAN SE, I could detect no audible noise. It was not until I switched the gain on the micro iCAN SE to 24dB that I started to hear a less than perfect black background. However, regardless of the headphone, under no circumstance would I, or probably anyone for that matter, ever be needing 33dB of gain on an iFi stack outside of attempting to amplify a phono source, and iFi makes the micro iPhono2 for that application!

Plugging in my HD 600, I loaded up Audirvana and pushed play, on random, because that’s how I like to roll! At this point I decided to throw all my previous experience and expectations with tube buffers out the window. Judging by the iFi products I own as well as what I was hearing (or rather not hearing), I knew the micro iTube2 will be a world apart from all I have tried before. What I was not prepared for was the magic that was about to be unleashed! With 3D and XBass off, I started with the ‘Classic SET’ Tube+ setting. First up was Dukas - The Sorcerer’s Apprentice as performed by Telarc’s Cincinnati Pops Orchestra, and I was floored! Every note was rendered with such smoothness yet possessed enhanced texture as well as greater focus, all while maintaining transparency with no loss of detail! Moving along to the ‘Classic Tube’ setting, I was immediately greeted with the familiar classic sound of the GE 5670 JAN, un-like I have ever heard before; The micro iTube2 fully unleashed the true potential of the GE 5670! Adding in both warmth and crispness, the soundscape became more expansive, full of weighted air that allows sound to bloom with a sonic delight! What can best be described as “ the best of both worlds “, switching to ‘Push-Pull’ proved to be the setting that many times caused my eventual drifting into hours of what can only described as meditative audio-nirvana!

Lets go over some of my overall impressions of the Tube+, shall we? As previously stated from iFi above, there is no right or wrong setting to use, and is completely dependant on both the listener’s preference as well as the source. While I completely agree with that statement, often finding myself switching modes depending on what headphone I am wearing as well as what track is currently being played, the actual naming of each setting, technically, is somewhat ambiguous. Class-A SET power amplifier, classic tube amplifier, and a push-pull tube amplifier, all describe the basic fundamentals of a device such as the micro iTube2. Reading them, I find myself saying “ Uhm, yes? ”. I do however understand iFi’s reasoning behind their labeling, and I will do my best to describe what I think each of the three settings is trying to achieve.

Classic Single-Ended-Triode Power Amplifier: This setting can best be though of as passthrough or neutral, with an added bonus. The classic tube effects are the least prevalent on this setting, and the source retains most of it’s original sound signature. However, this setting can also be though of as the original micro iTube’s ‘Digital Antidote Plus’! While the overall presentation of the source remains virtually unchanged, the sound now possesses an very analogue smoothness to it! There is added weight and warmth to both the bass and midrange, the treble has an added layer of crispness, and there does seem to be greater focus, but in no way would I describe it as adding colouration to the sound. Simply put, there is no frequency deviation from the source, only the addition of even ordered harmonics, or saturation, to the sound.

Classic Tube amplifier: The name of the setting says it all, and is the most prominent of the three. While I could use clichéd terms like expansive, weighted, warm yet airy, powerful and crisp, and I would not be wrong in doing so, this setting is so much more, and the best way of describing what I hear would be smooth-voluminous-analogue-tube-magic! As previously mentioned, this setting literally brings out the true potential of the GE 5670 JAN and punches you in the ears with it’s breathtaking sound!

Classic Push-Pull amplifier: 50% SET, 50% Classic Tube? Like Classic SET, but in hyperdrive, or perhaps Classic Tube on steroids? Actually, I tend to think of this setting more as the-complete-sound! Saying it’s the best of both world’s is simplifying things too much. I would best describe the sound as breathtaking, unbridled, powerful, pure class-A SET perfection! Or magic… definitely magic!

In regards to the 3D+ and XBass, I won’t be giving any thought and impressions in this section of the review. They are simply not applicable to me. The vast majority of my listening involves my headphones and my iFi stack, and this portion of the review is focused around just that. 3D+ and XBass are specifically designed with the use of loudspeakers, not headphones. Sure, one can toggle either and it “may” sound pleasant with their headphones, but let it be known that 3D+ and XBass on the micro iCAN (SE/BL) do a far greater job at their respected functions for headphones than the micro iTube2. In terms of their basic functionality, they are pretty straight forward and iFi does such a great job defining them that any words of mine would be nothing more than redundancy. I will however be covering numerous application in the upcoming paragraphs, which will include the use of both features. Much like Tube+, both redefine what I thought was possible in such a compact device, and will not be overlooked!

To end off my initial thoughts and general impressions, I was correct in forgetting what I knew, or thought I knew, of how a tube buffer should perform. Introducing rich saturation and unadulterated musical bliss, track after track, no matter the genre, the micro iTube2 exceeded my expectations in which I experienced no negative qualities whatsoever! From both my readings as well as personal experience, adding a tube buffer into the chain will always have a give/take relationship with the sound. For example, while the bass may become more defined it can lose impact, or the soundstage may become more expansive but at the same time the treble can become more harsh. Not so with the micro iTube2! There was no perceived colouration to the sound, no audible attenuation/accenting, no clipping, basically zero negative distortion! It mattered not the Tube+ setting nor the song played, the micro iTube2 simply enhanced the sound to a musical level my ears have yet to experience up until now!

Impressions (Application Specific)
* All testing was done using a variety of controlled A/B and sources that would be too numerous to list, as well as add in unneeded bulk to the review

Audirvana—> iPurifier2—> micro iDAC—> micro iTube2—> micro iCAN SE—> any headphone

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To start off this section, lets begin with synergy. First, a definition: Synergy is the interaction or cooperation of two or more organizations, substances, or other agents to produce a combined effect greater than the sum of their separate effects. From their aesthetics to their features, the whole of iFi’s micro line of products are designed to operate in perfect synergy with one another. While the micro iTube2 is a multifaceted device, it’s main functionality is to be stacked onto other iFi devices, meaning there is the ability to mix and match settings for headphones. This is where synergy comes into play. Regardless of what combination I tried, there was never an instance where I got a sense that the features of the micro iTube2 were conflicting with that of the micro iCAN SE, quite the opposite in fact; Every feature was completely complimentary!

Engaging XBass in no way muddied the sound, nor did it accentuate or detract. Bass, no matter on high or low boost, remained incredibly controlled; The micro iCAN SE kept an absolute grip on the low end, regardless of the Tube+ setting on the micro iTube2! I am not sure how, but the tube magic introduced by the micro iTube2 enhanced XBass to a whole new level of ‘wow’! Both texture and definition were kicked up a notch, a sign no sluggishness has been introduced, while impact and sub-bass alike received added saturation and weight. One major take away to note would be that in no way does the micro iTube2 boost the low end, it simply adds what was missing.

With 3D+ engaged, I half expected that engaging 3D+ high on the micro iCAN SE and using ‘classic tube’ or ‘push-pull’ would result in an overload of soundscape expansiveness, like engaging Dolby Headphones and SRS at the same time; yuck! Well, things got real! Much like XBass, it mattered not which combinations I tried, the result was nothing but a complimentary enhancement! The sound remained coherent with the effects of both devices melding into an effect that seemingly makes the headphone disappear!

Overall, I am more than impressed with the absolute perfect synergy between iFi’s products! Call it what you want, magic or great engineering, when it comes to the mixing and matching of desired enhancing features à la carte, there really is no wrong way to go considering there are zero negatives to be had! On there own, every toggle function outperforms many over-engineered/over-priced products, as well as ones who’s selling points overshadow their actual performance. Add in the fact that you can combine multiple toggles to shape the sound to your desire, all while the stack maintains absolute control of the sound, is nothing short of impressive! Or perhaps even magical!

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Audirvana—> iPurifier2—> micro iDAC—> micro iTube2—> micro iCAN SE—> Sennheiser HD 600, AKG Q701, Grado SR60e, PSB M4U 1, Meze 99 Classics/99 Neo

The Sennheiser HD 600, AKG K70X, and Grado Prestige series are probably the three most popular open backed headphone lines in current production, thus the headphones used for this section are a good representation of what the average end user may own. Closely resembling the sound presentation one would expect from a loudspeaker, their open design gives the user a more natural listening experience, but they are not without flaws. One common complaint myself and other have with open back headphones in general is the subdued bass impact, weight and resonance. Regardless of how well textured and defined it may be, without having and enclosed system such as a closed backing (or in respect to a loudspeaker, a room) the low end tends to flutter out and suffer due to the lack of reflecting surfaces.

Using the Classic SET setting, without engaging XBass on the micro iCAN SE, the micro iTube2 re-introduced all that was missing from the low end to both the HD 600 and Grado SR60; Impact and weight. Admittedly, for the Q701 I did have to engage the lowest XBass setting to achieve satisfactory results, but hey, that’s what the feature is there for, and now the bass has, what I consider, proper impact and weight! For both the SR60e and Q701, another common issue many have is the upper midrange and lower treble. While well extended, for some this range of frequency can sound too hot, too piercing, and thus fatiguing, and I am no exception. The micro iTube2 manages to smooth over the troublesome regions, providing a far less fatiguing sound yet does so with no loss of resolve or detail! Try as I did, I was unable to detect anything missing from the music, nor did I encounter any drop out or roll off when playing test tones/sine sweeps. One thing I did find with all three headphones is that overall the sound stage seemed more contained, more defined. What I mean by that statement is that I am hearing more of the track’s recording environment(s), something that is more prevalent in closed back headphones, yet the natural openness has not been diminished!

Moving along to the closed back headphones, the PSB M4U 1 and both the Meze 99 Classics and 99 Neo all share a common sound signature; Slightly elevated yet well extended bass and controlled bass, silky smooth liquid like midrange, and a crisp, fatigue free detailed treble that offers the perfect balance of sparkle and air. They are wonderful performers and very well received within the community. Keeping with SET and starting with the PSBs, I immediately noticed how much more relaxed the upper mids and lower treble are when at a higher volume. On certain tracks at higher than normal listening levels this region can become somewhat strident for the M4U 1. Like magic not an once of detail is lost, yet much like the afore mentioned Grado and AKG this region of the frequency response became less fatiguing! Bass weight and impact became more apparent while the lower midrange was enhanced with greater texture and focus! Both Meze faired equally as well in that micro iTube2 did nothing but enhance what was already great sounding headphones! Texture popped with a greater focus throughout, bass became more weighted yet remained controlled, and the treble received a good does of a natural sense of air while maintaining it’s crisp nature!

While the micro iTube2 essentially enhances the sound of both closed and open back headphones in a similar manner, it is interesting to note that in regards to the sound scape the behaviour is the polar opposite. For open backed headphones, the micro iTube2 seemingly adds a greater sense of the room. While maintaining their openness, there is a far greater focus on the boundary of the sound, much like a closed back headphone. It is the reverse for closed back. Because of the nature of their design, there is no missing sense of boundaries as the sound is enclosed within the cup. What the micro iTube2 adds is a greater sense of air and space to the soundscape, giving way to a sound more akin to a open air headphone! Impressive!

Both the classic tube and push-pull settings yielded results that went beyond my expectations, regardless of the headphone. While the bass became more solid, even coherent overall, what impressed me the most is the return of resonance… kind of. SET brought greater bass weight and impact, but classic tube and push/pull introduced a large, voluminous sub-bass! In no way is it boosted, rather saturated and expanded! Adding weight and air to the midrange, texture is brought to a whole new level with much greater focus and resolve. Treble also gets a boost thanks to the the increased saturation, creating a more crisp and defined upper range without negating any sense of natural air! Lastly, the soundstage became more focused and expanded, almost as if invisible boundaries were created thus providing a greater sense of imaging, yet still maintained the openness the style of these headphone produce. I have always been quite content with the sound of these headphones, they are all well reviewed and respected, but the simple inclusion of the micro iTube2 brought them to a whole new level of audio excellence! Nothing sounds boosted nor out of place, simply enhanced in a natural and organic way!

Before I round off this section, I have to give special props to both the HD 600 and 99 Classics. Earlier I talked about synergy, well, the HD 600 and the iFi stack are the epitome of the word! I don’t think it’s too far fetched to assume that the folks at iFi have this headphone readily on hand, nor would it be to likewise assume the HD 600 is the final step in their testing. I am having trouble finding words to describe their relationship, other than they are a match made in Heaven! Unadulterated, pure music magic! Including the micro iTube2 into my stack has not only made me appreciate the HD 600 to a greater level, it has re-ignited my love of these legendary headphones!

Not to be outdone by the HD 600, the Meze 99 Classics and micro iTube2 share perfect complimentary symmetry! Unlike speculation about iFi and the HD 600, I know the folks at Meze have iFi products sitting at their desks; I have seen the pictures! They don’t lie, and neither does the pairing of the two. Simply put, the micro iTube2 enhanced the “classic” of the Mezes and took the already phenomenal sounding headphone to the next echelon of listening enjoyment! Well done guys!

Audirvana—> iPurifier2—> micro iDAC—> micro iTube2—> Yamaha HTR-6040 Natural Sound receiver —> Klipsch WF 34 Icon loudspeakers

Over the years I have gone through great lengths to bridge the audio from my computer to my home theatre system and achieve optimum sound reproduction. The problem stems from the distance between the two, and how to connect them without introducing interference. Most people, like myself, will simply use a standard RCA that is long enough to reach, which is fine for short runs, but once the distance spans greater than 15’ there is a good chance that the signal will start to break up and artifacts introduced. Buzzing, hum, clicks, noise, fuzz, even radio stations, I have heard it all! This is why XLR or balanced cables were created. I however do not have this luxury. My solution to achieve a clean, uninhibited signal was to purchase a TosLink (optical digital) booster and use a 20’ optical connection from my computer to my receiver. This means that over the years I have missed out on using my Audioengine, my TEAC, and now my micro iDAC, and relied solely on the Yamaha’s AKM DAC. Enter the micro iTube2!

When it came time to test the micro iTube2 with my home stereo, I was admittedly at a loss as to how I was going to get the audio from the iFi stack to the receiver. Do I temporarily move my whole computer closer? Maybe chain a few powered USB hubs together and move the iFi stack closer? Then it dawned on me, and I felt pretty silly for not realizing this earlier. By design, a pre-amp is a signal booster! So I now had a solution: bridge the micro iTube2 between the micro iDAC and my Yamaha receiver using 2 short RCA cables! Duh! So after I got over my blonde moment I dug out a pair of 10’ audiophile grade RCA and made it happen. This actually worked out great as my listening position just happened to be at exactly 9’ away from both my computer and my stereo, meaning the micro iTube2 was able to sit on my coffee table, thus allowing me to easily select and control the various settings! Yeah, I now have thick RCA cables running across my floor, but it it is a small and temporary price to pay for a clean, unhindered signal!

The Klipsch WF 34 Icons are not only perfectly angled to 30° but perfectly spaced and distanced from each other and the walls. I opted for 3D+ and XBass to be disabled, and started things off using nothing more than SET. The moment I pushed play the inclusion of the micro iTube2 was noticeable; Smooth, warm, inviting! My Icons never sounded so sweet, so analogue! Bass became more impactful, the midrange gained a nice layer of warmth leading way to fantastic texture, and the treble completely smoothed over becoming less fatiguing yet more detailed and focused! I always thought the Icons were detail monsters before, but SET added such beautiful saturation that I am hearing not detail that I have never heard before rather hearing detail presented in a way I have never experienced before!

Things were starting to look very promising, so I decided to switch on XBass 6dB gain. I have to note, the WF 34 Icons only reach down to 50Hz. Bass is solid and very impactful thanks to their kevlar reinforced fibre glass drivers, but it never really gave me that deep inner body sub-bass rumble. Essentially, my feet on the floor could feel the bass, my body could not. Engaging XBass is a whole different ball game! If I were to use the receiver’s bass tone control and give it a boost of 6dB the result is merely louder bass, while engaging XBass seemingly fills in the gaps and enhances the sub-bass to a visceral level! Wow, I am actually ‘feeling’ the sub-bass throughout my body! What I find very interesting is that with the receiver’s bass boost, anything that hangs on my walls will start to vibrate, however XBass lets me feel the music yet my walls remain unaffected! How is this possible!? Magic?

Moving along to 3D+ toggles, as the loudspeakers are angled to 30° selecting 30°+ would not be beneficial. For poops and laughs I did try, and the result was an over-focus and narrowing of the sound field, much like if the loudspeakers were toed in at a greater angle, and did not sound that pleasant. However, engaging the 3D+ was nothing short of amazing! I expected this setting would simply add greater width to the sound field, and it does in a way that sounds extremely natural and not forced. What I was not expecting is how 3D + seemingly pulls the sound away from the speakers and extends it outwards! I have heard many 3D enhancers both software and hardware driven, and they all sound like a DSP. 3D+, simply put, organically enhances the soundscape to a degree that I can’t put into words other than it has to be heard to be believed!

Keeping with 3D + and XBass 6dB, the real magic began once I toggled Tube+ from SET to Classic. The first track to play was Nah Neh Nah - Vaya Con Dios and my jaw hit the floor! I literally had one of those moments where the hair stands up on the back of your neck, eyes start to water, a chill of excitement flows through your veins, and you forget to breathe! Such life, such flawless beauty, such emotion and excitement! My senses were ignited, and I was in another dimension completely detached from this reality! It was like I was placed front and centre in a cabaret hall with a private performance of Vaya Con Dios for only myself! Every nuance of the sound came to life and was brought to the forefront. Nothing sounded coloured, bolstered, or distorted negatively; Simply natural, organic transparency! Just…wow! In all honesty, I had to mellow out and compromise with Push/Pull for a while after; Tube+ was just too darn good!

To sum up this section, all I have to say is that the micro iTube2 enhanced my home stereo to a level I never thought was technically possible outside of purchasing all new components! Call it wizardry or a technological marvel, I have upgraded both speakers and amplifiers to a much lesser effect than what the micro iTube2 adds to my music, bar none! iFi really knows both their engineering and what is lacking in todays modern home audio solutions, and redefines what I thought possible in a SET tube pre-amplifier. Hearing what I have heard there is no going back to the old way; My ears will not allow it!

CPU—> iPurifier2—> micro iDAC—> micro iTube2—> Lepy LP-2020A —> Mission Model 80 monitors

The Lepy and Mission combo fed from my PC’s on-board audio is what I use for my desktop audio set-up, and is used almost exclusively for watching streaming videos. It’s not fancy but it gets the job done by providing decent performance while taking up the least desktop space. Including the micro iDAC and micro iTube2 into the mix really stepped up the sound, by a large margin! It was like a upgraded my amp! Simply by using nothing more than SET toggled, the first thing that became apparent was the smoothness of the rendering. The digital harshness typical with class-D amplifiers dissolved, leaving only a classic analogue sound! Of course, switching things up and selecting the other two Tube+ settings yielded expected results; Enhanced bass, greater texture, and a more open soundstage!

Normally, the Missions are angled to 30°, so to test out the 3D Holographic+ 30° option I moved them flush against my monitor. I must say, the implementation of the 30°+ setting is absolutely spot on! To my ears, I heard very little deviation of the soundscape between having the speakers naturally placed at 30° or with the 30°+ toggled. Everything sounded natural and organic, and not forced; Very impressive! Moving the speakers back to their normal angle, I engaged 3D + and what I heard was identical to my WF 34 in that the sound, like magic, seemingly detached itself from the cones and expanded outward! While the effect was not quite as prevalent as my loudspeakers, it did give a greater sense of size to the monitors as well as the accompanying sound stage!

Not to overlook XBass+, but for my application and use of this set-up I found this option to be not needed, and in all honesty too much. Engaging 6db was enough to cause distracting vibration of my desktop, and at 12dB gain the amp starts to show signs of distortion. I will say this though, compared to the bass pot on the Lepy, XBass+ 6dB does a far greater job at enhancing the bass providing a clean, impactful sound without sounding like a cheap inclusion as with the LP-2020A!

(Hitachi 46” LED) HDTV—> micro iTube2—> Genius GX 1250 amp—> Nuance 101 monitors

For many years now this has been the setup I use for TV viewing. It is a nice combo, with the 20W class A/B amp providing decent power and sound to the 100W monitors. The sound is miles ahead of the TV’s built in speakers, and destroy what a sounder could produce! Unfortunately, due to their large size as well as the overall size of my sunken living room in relation to my Klipsch loudspeakers, the placement of the monitors have to be flush against the TV. I could angle them to 30°, however only 1 person on the couch, me, would receive the benefit of the speaker’s positioning. A simple flip of a switch would remedy this issue!

The TVs I have owned in the past all had some sort of SRS 3D, Dolby Virtual Surround, or some form of generic virtual surround, and most were, at best, neat sounding. They were somewhat effective, but essentially amounted to nothing more than a gimmicky selling point. 30°+, simply put, not only brought the wow factor to the monitors but put all other implementations to shame! Much like with my desktop setup, the monitors did indeed sound like they were in fact angled at 30°. Unlike my desktop setup, because of the 9-10’ distance between me and the monitors the perception of the effect was much greater; No matter where I was seated on the couch (or even standing in the room) the effects could be heard.

Just to note, I did engage both XBass and 3D + to give them a try. While latter setting magically pulled the sound out and away from the cones, the effect was not as satisfying as 30°+. XBass, once again, was not too applicable in this setup as the monitors have the capacity to reach down to 20Hz. Engaging 6dB XBass gain was fun, 12dB probably angered my neighbours, but essentially both are not needed. As with anything, YMMV. In this particular setup 30°+ was enough to bring a more than satisfying TV watching experience.

iPod Tough 6th Gen.—> micro iTube2—> Topping NX1s

While the micro iTube2 on it’s own ins’t considered an OTG device, I thought I would include this combination as I know of many who use a portable music player in conjunction with a portable amplifier for use at their desks away from home. However for this chain I won’t be including my impression on the sound, as it would be redundant, rather speak about functionality and ergonomics. This is where using the micro iTube2 as a pre-amp comes in very handy.

Having 3 devices in a chain that each has their own separate volume control can be a mess. Most digital devices have digital volume (duh), which means you have the potential to not only lose ‘bits’, but have a nasty step progression in it’s adjustments (i.e. one click up equals 3dB , then 2dB, then back to 3dB and so on). As well, most portable devices do not have a separate line out jack. To remedy this with use of an external amplifier, the headphone volume output will be set to max out on the source device. However, depending on the internal amp, you can also get double amping as well as a difference in the output impedance, which in most cases alters/degrades the sound. Not ideal if you want the absolute best out of your demanding headphones.

Besides the plethora of enhancements and features previously covered, in this scenario including the micro iTube2 into the chain has two benefits. Firstly, because a pre-amp is essentially an analogue sound processor, it will take any signal and change it into something that is universally accepted. It matters not what signal is being fed in because the micro iTube2 will always output essentially an optimum amp friendly signal. This ensures that you are getting the absolute best quality of signal being passed through. Secondly, the pre-amp’s analogue volume pot can be used to adjust the output, forgoing the external amp’s. Besides ease of use, this also allows the user to adjust the volume to a much finer degree!This is very useful as most people who use a portable music player with an external amp also have the two devices banded together, making any volume adjustments rather cumbersome. Essentially one would set the amp’s volume once and use the micro iTube2’s analogue pot to make any further adjustments. Another benefit would be clutter and cable management between the devices. One could easily set the player/amp on top or beside the micro iTube2 hand have the leads snaking behind. Great for people like me who despises desk clutter and is constantly clearing away mess like I have OCD.

iPod Tough 6th Gen.—> micro iTube2—> Sanyo MCD 950

Just when I thought I had tried just about every combination available to me, while working on a project in the basement it dawned on me that I had overlooked my “work tunes”. Normally while at either my work bench or work out bench I listen to my Sanyo shelf unit being fed by my iPod. It’s a rather nice albeit 30 year old twin CD boombox featuring a dual woofer bass chamber. Back in the day this was considered top on the line, and has served my family well before making it’s way into my possession. I have to say, and not to my surprise, adding in the micro iTube2 turned this now vintage gem into an absolute delight to work to!

Setting the boombox to flat EQ with the bass port on low, I started off with 3D + default and SET and was greeted with a pleasant warm expansion of the sound width. Not too bad in terms of achieving a smooth and expansive sound from such a unit. Switching things to 30° was a whole different animal! The sound seemingly detached itself from the unit and expanded outward! While the “sweet spot” was rather small, depending on the distance from the boombox, the effect was large enough to be heard several feet away regardless if I was seated or on my back. However, the combination of 30° and Classic Tube or Push/Pull blew my mind; The sound was now presented in what I can only describe as a 3D vacuum bubble! All I can say is wow, I didn’t think it were possible to achieve such a large expansive sound from a boombox! But what about XBass? Literally Earth shaking! By simply toggling 6dB, no matter what the bass tube was set to, the micro iTube2 brought power to the low end, so much so that I could feel the increased air pressure the ports were exhausting! Switching up to 12dB and having the chamber fully open was too much… for the wife upstairs… but oh was it glorious!

All in all, I was pleasantly surprised at how much the micro iTube2 could enhance a boombox! While I am not too sure if I would continue using the combination, it is not because of the hassle of unchaining, then bringing the micro iTube2 downstair, and chaining things back together. Nope, it is because I don’t think I would get any work done! Having background tunes is one thing, but I wouldn’t get too much accomplished if I spent most of the time more engrossed in the music!

Storey Time: Road Trip!

Because iFi’s micro line of products share a common power requirement, I was able to make use of my 15V 2A battery power pack I whipped up for my micro iCAN SE and take the micro iTube2 on the road! As stated, my family is composed of musicians and professionals. While I have a good selection of gear to try, what my brothers have fills the gaps. The micro iTube2 is so versatile, I simply could not overlook the opportunity to try out and showcase to those who would appreciate what the device brings to the table.

I do have to note though, there was some cable wizardry going on in connecting the micro iTube2 in most of the below cases, so for simplicity sake accept the chain and don’t think too much on the connectivity rather the results.

Panasonic DMP-BDT700—> Onkyo M-3000R DAC/Pre-amp—> micro iTube2—> Onkyo M5000R Amplifier—> Proac Response D38 loudspeakers

My eldest brother is the one who lead me down the path of the audiophile. Being a purist himself, his audio setups were a thing of beauty, both in topology and performance! What he currently has would be considered unattainable to the average enthusiast. Before reading any further, please, take the time to do a quick search of the components listed, maybe even read a few reviews. It’s cool, I don’t mind! This is his end-game, and hot diggity dog does it sound heavenly!

I had originally popped in to play with his HTC Vibe and get a little VR time in before we had to attend a gathering at my parent’s, but I had ulterior motives; I HAD to try out the micro iTube2 on his dream system! I did not inform my brother I was bringing the micro iTube2, I knew he would have lectured me on how tubes are inferior to the semiconductor. He is the type who’s vast music collection is on CD, and will quote Nyquist whenever Hi-Rez audio is mentioned! So when I arrived I sprang the device on him and right away, and he started to state his opinion on why he doesn’t think a tube pre-amp would be in any way beneficial to the sound, as predicted. I told him to “ Trust me, this is going to be good! “ and proceeded to chain the micro iTube2 between the pre-amp and amp. His reaction was kind of meh, but he sat down in the sweet spot and indulged my demonstration.

Starting off with Dire Straits Money For Nothing (original Brothers in Arms CD release), I set the micro iTube2 to SET and 3D + and pushed play. To receive the full effect, I stood behind him both listening and watching his reaction. As the melodramatics of the lyrics and synthesizer slowly faded in, followed by the powerful room filling drums and the eventual iconic guitar rift, I could feel the impact of the micro iTube2 immediately, and wow did it sound amazing! I really don’t like using this cliché, but it was as if I was hearing the song for the first time! The subtle nuances that were brought out, the full impact of the bass, the spacious room filling sound, and the organic smoothness can only described as (apologies for the crudeness) an eargasm! Looking down my brother had the all too familiar “silly grim”! I think he was impressed to say the least.

As the song is over 8 minutes in length, about half way through I went over and turned down the music and asked “ Well? “ and he replied “ Turn it back up! “, and I obliged but not before toggling Tube +. His reaction was priceless. If anyone remembers the only BASF tape magazine adds, the one where there is a fellow sitting in an armchair in front of a stereo who is literally being blown away by the sound, that would be my brother! I must admit, returning to the spot behind him yielded a similar reaction! Holy H E double hockey sticks did it sound amazing! The next hour and a half was spent toggling various settings on the micro iTube2 and swapping out CD after CD, an exhausting effort, but it was so worth it and I really didn’t mind. A small price for perfection I’d say!

Before we ended the listening session, it occurred to me that I had overlooked something; Removing the Onkyo pre-amp from the chain entirely! Relying on the Blu-ray player’s DAC and using the micro iTube2 as the pre-amp alone to the main Onkyo amplifier, my brother and I were more than impressed with the results. While there was a slight loss in refinement, the micro iTube2 managed to trade blows with the much, much more expensive pre-amp while enhancing and enriching the sound with blissful tube magic, something the latter could not! In the end, my brother made the remark that perhaps after he upgrades his computer’s graphics card, he may just pick up a micro iTube2 for himself. Nice! In my opinion, it is an absolute must have for him; It would be a disservice if he didn’t! Who needs flawless, silky smooth VR anyway?

Jackson Flying-V—> micro iTube2—> Marshal Amplifier

The next three sections are a result of yet another family gathering, this time at my 2nd older brother’s; I have three, one younger and 2 older, and they are all audio and tech enthusiasts in one way or another. Anyway, my younger bro had stopped by to pick my wife and I up to carpool to the event. As we were getting into the back of the truck, he turned and said “ Watch out for the guitar… “. I replied “ Guitar? Hmm… “ and it struck me, why not add a little bit of classic tubiness and bring the micro iTube2! I quickly ran back inside and grabbed the device. “ What’s that? “ he asked. “ Oh, you guys will see… “ I smirked!

Shortly after we arrived and got settled in (beers and munchies) us brothers went down to the basement for a little rocking out to the game Rocksmith! My brother brought his Jackson because he could not stand to use the pack-in basic electric guitar, a move appreciated for those who would be playing. Myself, I am not musically inclined, so I would merely be a spectator. Connecting the flying-V to the small Marshal amp the rocking out begin! I did not immediately bring out the micro iTube2 as I wanted to get a good impression of the guitar/amp combo sounded on it’s own. After a few rounds, I decided it was time! During a quick vape break, I connected the micro iTube2 and awaited their return. Almost instantly my older brother noticed the device chained in and asked what it was. I told him it was a tube pre-amp and his eyes lit up! “ No way! “ he exclaimed as he crouched down to take a better look. My younger brother wasn’t sure what a tube pre-amp was, but we filled him in and he replied “ Cool! “, and the jamming out resumed!

Starting off with only SET enabled, like magic the sound was transformed into what can best be described as a classic, warm, pleasantly distorted, fat sounding grittiness! We were all in amazement of the amplified sound coming out of the small amp! Toggling the Tube + and Push/Pull were equally impressive, both enhancing the airiness of the higher registers and adding organic crunchiness to the midrange texture. Adding the micro iTube2 transformed a modern run-of-the-mill amp into something more akin to an actual classic tube based amplifier. However what impressed all of us the most was the ability to push the micro iTube2 in terms of power without any break-up, something that is very common in classic tube based amps! You get all of the benefits without the usual disadvantages!

In regards to both XBass and 3D+, neither setting really benefited the sound, and in some way just sounded weird or unpleasant. The latter really needs to be stereo for full effect, and XBass seemed to overdrive the sound too much resulting in negative distortion. I consider this in no way a shortcoming of the features as in actuality, in this application, neither really makes sense to use.

Technics 1200 turntable—> micro iTube2—> M-Audio Project Mix I/O—> M-Audio M3-8 powered monitors

Once fingers tired, it was time to move on to something less physically involving. Being a DJ, songwriter, and mixmaster, my brother has a pretty good set-up to record and master tracks. Of course, what professional in this genre would not have a decent turntable, and my brother is no exception. “ What do you got for vinyl? “ I asked. He responded by removing a cover, exposing a classic Technics 1200 turntable. My eyes lit up and I started to say “ Is that the one… “ and was interrupted with “ That’s THE one! “. You see, in our teen years he had picked up the legendary Technics 1200 and it has been serving him well ever since. I have quite a few fond memories with that baby. I knew I we were in for a treat, and so did he! With a wide range of albums to sample, ranging from Queen, Boney M, New Order, and Björk us brothers, with beers in hand, sat back and absorbed the the classic vinyl sound!

The settings used was 3D+ enabled as the monitors were already angled, and XBass was disabled because the they have no problem reaching the lower registers. I figured that SET and Push/Pull to be too smoothing for vinyl (eventual testing proved my suspicions correct), so only the Classic Tube+ setting would be used. Normally, I find vinyl to sound rather flat, and lacking dynamics when compared to modern digital music, but the inclusion of the micro iTube2 injected all that I find lacking with the format! The sound came to life with a greater sense of expanded air and space, as well as greater focus of individual instruments and effects. Dynamics were enhanced and brought a much greater level of excitement; Bass possessed a nicely weighted bloom, the midrange texture gained a smooth and organic quality, and the treble became more crisp and well extended, with a much greater sense of natural air! Both my brothers couldn’t get over how much of an enhancement the micro iTube2 brought to vinyl, and to be honest neither could I! It was pure magic!

AKG C314 Mic—> micro iTube2—> M-Audio Project Mix I/O—> M-Audio M3-8 powered monitors

There was one last piece of audio tech that was staring me in the face, begging to be paired up with the micro iTube2; An AKG C314 microphone! “ Hey, can we try out that bad boy? “ I asked pointing to the mic. “ For sure! “ my brother replied “ There are actually microphones that have built in tube buffers. This should be good! “ and it was. 3D and XBass disabled, starting off with SET brought a wonderful enhancement to the already stellar sound. All 3 of us were adding in various Tom Foolery and no matter which voice, the resulting sound was smooth, detailed, well textured and possessed a classic richness to the tonality! Switching to the Classic Tube + and Push/Pull resulted in a more airy and crisp sound while simultaneously enhancing the natural texture and focus of both the lower-mid and midrange frequencies! Eventually, our voices were sampled and added into various tracks my brother was working on. It would have been pretty cool to include some of the audio we sampled, but on further thought the content wasn’t too crass to be review friendly. All in all, we had too much fun with the the micro iTube2! It was very rewarding to hang with my brothers, but to do so over fine spirits and great sounding music was priceless!

Value

At $375 USD, unparalleled, the micro iTube2 is a tube output stage, active tube preamp, tube buffer, as well as an impedance-matching device all in one package. If I were judging on versatility alone, the the micro iTube 2 would be more than fairly priced. The inclusion of the super sleek and sexy aircraft-grade CNC-aluminium anodized shell, top quality reference class components, and the 15V iPower make the micro iTube2 one heck of a deal! Sprinkle on some tube magic of iFi Audio’s class-A engineering and the micro iTube2 is a must have for any audiophile and enthusiast; There literally is nothing quite like it!

Conclusion

In closing, I can not help but think of the line from The Million Dollar Man: “ We can rebuild him. We have the technology. We can make him better than him was. Better, stronger, faster. “. Once hailed as the “Swiss army knife” of pre-amps, the micro iTube2 is not simply an upgraded model to the original, rather a complete redesign built upon trickle-down flagship topology. If I had to choose a word to best describe the overall qualities of the micro iTube2, it would be magic: The power of apparently influencing events by using mysterious forces, a quality of being beautiful and delightful in a way that seems remote from daily life, exceptional skill or talent! Bringing the analogue back to the music in today’s digital world is no small feat, yet with the micro iTube2 iFi defies what was once though impossible and delivers a 100% class-A SET tube buffer and pre-amp that not only magically re-introduces the forgotten natural harmonics but does so organically with absolutely zero negative effects! I don’t think I have ever encountered a device that has been as impactful on my music than the micro iTube2! It’s not often I label a product as a “must have!” (in fact, never), but given it’s price, outstanding features (that are border line magic!), flawless performance, and extreme versatility, if one is serious about their music the micro iTube2 is a must have and should be your next upgrade! Period!
Condocondor
Condocondor
I disagree with not hearing any difference after a break-in period. I began to notice a significant difference after 15hours and a serious difference ater 24 hours of break-in that started to show the magic the iTube is capable of. Tubes do require break-in time.

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