September 2013


iFi micro iTube 'Swiss Army Knife'
Hi-Fi's most funky box of tricks?
Review By Clive Meakins

  ifi don't need much in the way introduction now as they are well established as an off-shoot of AMR. Some of their diminutive and very affordable products use technology trickled down from their AMR big brother. This time the technology inside the iTube is very much all iFi. The iTube uses the now familiar iFi designed plug-top power supply and iFi extruded aluminum casework.

iFi position the iTUBE as a Swiss Army knife of HiFi and it is so. It can be configured:

  As a buffer with zero or 6dB gain
  As a single input preamp with zero or 6dB gain with manual volume control
  To tailor bass spatial location to the way our ears work
  To ameliorate digital edge and harshness

It would be all too easy to dismiss the iTube as a gimmick; seriously, do not be tempted to do this. The iTube is a very well-conceived piece of kit. I must confess that when I was told what the iTUBE does I was a little skeptical about it; had it been April 1^st would have been thinking I smell a rat. There is no rat; instead it's something every music buff should consider buying. Was asked to ensure I ran the iTube for a full week 24/7 and duly complied... and then some; I grabbed an occasional listen and can confirm the sound does improve with burn-in.

The iTube has a warm heart; the heart is a miniature NOS tube, a GE 5670. This conservatively run tube endows the iTube with a pleasing warmth to the touch. The dot on the iFi logo is a hole above the tube providing ventilation and red glow confirming operation. Neat.

Looking at the underside of the extruded enclosure reveals a set of DIP switches for you to set some of the iTube modes. It comes with a tool for you to use to flick the switches, a set of interconnects and power lead adapter you may find useful should you not want the power lead firing a long way out of the side of the iTube. The functions you'll need in daily use are accessed via two switches on the front panel and there's also the volume control which only operates in preamp mode. Most of my listening was done with my system setup with the following:

  Trans-Fi Salvation record deck, Transfiguration Spirit cartridge, iFi iPhono
  JPLAY into Metrum Octave mkII DAC with iFi iUSBPower
  Bent Audio AVC-1 preamp
  LadyDay LD91 300B SE power amps
  Two XTZ Sub Amp 1 DSP
  Bastanis / Trans-Fi hybrid open baffles speakers

Buffer Without Gain
As a buffer the iTube offers an extremely easy 1M ohm input impedance. In my time I've used the solid-state Burson Buffer and the tube-based Musical Fidelity X10D. The X10D was far from transparent, it gave warmth but added grunge. The Burson Buffer is way more transparent, seemingly adding little sonic footprint.

My first aim was to check how well the iTube performed as a buffer, was it transparent? I found that insertion loss due to introducing the iTube into my system is frankly very hard to detect. I'm not confident I could reliably tell you whether or not the iTube configured as buffer was in my system or not, except perhaps with the very best recordings.  The very best recordings are just ever so slightly less open and airy with the buffer; the difference though is incredibly small indeed. You might think this renders the iTube buffer redundant; it does as a buffer in my system because I don't need a buffer but a lot of people with passive preamps will benefit from using the iTube as a buffer. The key point for me is that the buffer is as near transparent as is possible so I'm comfortable that by using the 3D HolographicSound and Digital Antidote Plus functions I'm not compromising my system with a worryingly degrading buffer. Should you need a buffer to better match your sources to a passive preamp and power amp then I foresee very worthwhile sonic benefits simply by using the iTube as a buffer.

Buffer With 6dB Gain
Using the buffer with 6dB of gain configured via the dip switches on the underside of the iTube I could detect no change in the sound versus without gain. I reduced my AVC-1 preamp level by 6dB to make this a fair test.

Preamp Without Gain
Next up was running the iTube as a preamp without gain; the sound was remarkably good. The main drop-off I noticed versus my far more expensive AVC-1 preamp was that the bass was not as tight as I'm used to. With lesser preamps I usually find soundstage width and depth are compromised, not so here. The iTube couldn't quite match the bass tightness, the overall openness and treble decay of the AVC-1 but the iTube put up one heck of a fight and that's without taking price into account. The iTube is easily good enough to be a serious alternative to many preamps, especially as it provided a friendly 100 kOhm input impedance. The downside is that there's only one set of inputs and outputs. Indeed the iTube was hampered in my comparison with the AVC-1 by my needing to use dual RCA adapters with the iTube as I needed the preamp to output to both my bass amps and main amps.

Preamp With 6dB Gain
When switching the preamp to give 6dB of gain I set the level to match how I was listening with zero gain. I struggled to hear much difference and if anything the sound quality improved ever so slightly in terms of bass clarity.

3D Holographic Sound
This function is intended to improve our ability to detect the location of bass instruments, there are 3 settings: Direct, Hi-Fi and Desktop. ifi went back to the work by Alan Dower Blumlein from the 1930s at the very dawn of stereo. This is linked of the Binaural patent by Blumlein. Essentially it's about our hearing bass frequencies differently that those higher up the spectrum due to the dimensions of the human head.

Direct – this simply operates as a buffer, switching out the 3D Holographic Sound.

Hi-Fi – with this setting bass is supposed to be better located by the listener.  Using a modern recording with a bouncy bass, in this case Caro Emerald / Deleted Scenes from the Cutting Room Floor, the drums became more distinct. There was less of a simple thump and more of a bass sound with shape and texture, it sounded more realistic. Moving onto Annie Lennox / Diva I found the bass guitar notes to be cleaner, the best way I can put this is that the bass notes were better described. I could not locate bass any better but it was time now to move onto analogue recordings to investigate further. With Sonny Rollins / Saxophone Colossus I could be sure real (i.e. nothing synthesized) instruments were being played so this should be a good test. Playing Moritat first of all I had to find a way to get myself to ignore Sonny's sax, which was a challenge. In HiFi mode the double bass sounded less thrumy, I could better hear the double bass strings vibrating; I could better locate Doug Watkins on double bass. A side effect of this more detailed and cleaner sound was that the double bass shrank back into the mix a tad. I simply turned my bass amps a little to compensate and all was good. In more typical systems it may be necessary to move the speakers a few inches closer to the rear wall to re-balance the bass.

Desktop – used on my main system, the soundstage became a little wider and now left and right seem to bend around towards the listing position almost like a control bridge on ship or a major computer installation but this is not how this mode is intended to be used, nonetheless it was interesting. I tried the desktop mode with my desktop/holiday system which is a laptop running Foobar2000/ASIO4ALL into a USB DAC and Creative Labs active T40 speakers. The whole soundstage expanded, switching 3D Holographic Sound out of the system resulted in a shut-in sound. 3D Holographic Sound works really well, the improvement in Desktop mode was dramatic.

Digital Antidote Plus
The purpose of this feature is to reduce digital harshness. iFi acknowledge the work by Anthony Taddeo in the 1990s and have built on this. There was a time when I could tell from outside a room whether a CD or record was being played; the spit present on vocals was a dead giveaway. Those of us with NOS DACs probably suffer least or quite possibly bought NOS DACs because we are particularly sensitive to spit and spitch sounds. iFi refer to the wider digital harshness issue "digititis".  The Digital Antidote Plus feature of the iTube curtails the ability to hear hardness on "s", "t" and similar sounds. Whilst the Metrum Octave mkII DAC I was using is very good in this respect there are recordings that are a still little too spitty for my liking, so I chose some of these. I found switching in Digital Antidote Plus was useful in providing a well judged compromise between fixing the problem and not wrecking the "presence band" frequencies. This is a great facility to have on hand, I found I used it more than I expected to.

Conclusions
It would be all too easy to dismiss this diminutive box of tricks as just as a plaything. This would be a mistake.

1) The iTube operates as a very useful buffer, assisting sources with a less than ideal ability to drive tricky loads, quite likely via a passive preamp.

2) The iTube preamp capabilities are surprisingly good, as a single input preamp it holds its own in my reference system in terms of sound quality.

3) The iTube spatial effects due to 3D Holographic Sound are of long-lasting interest,

4) The iTube Digital Antidote Plus does a surprisingly useful job in reducing "digititis".

You can place the iTube between pre and power amps, though in my case this wasn't viable long-term as I require two outputs from a preamp. For me it's not a question of whether I need an iFi Audio iTube; rather it's how many do I need? I could do with one iTube for my DAC, another for my phono stage and a third one for my desktop system.

Specifications
Type: Stereo analog preamplifier with audio 'enhancements'
Input Voltage: AC 100-240v, 50/60Hz
Input Impedance: 1M Ohm Direct Tube Buffer
   100 kOhm preamplifier with volume control
Output Impedance: <1 Ohm
Corrected Output Impedance: <200 Ohm
Dimensions: 175 x 67 x 28 (LxWxH in mm)
Weight:278 grams (0.61 lbs)
Warranty: 12 months
Price: $299, €299 and £275 including European VAT

Company Information
ifi Audio
E-mail: contact@ifi-audio.com
Website: www.ifi-audio.com