[Review] iFi iTube, Gemini D-H USB cable

iFi iTube

Pandora's box of hi-fi tricks?

Product name: iFi iTube pre amp
Manufacturer: iFi
Cost: 275 UK pounds.
(Currency conversion)
(YMMV)

Reviewer: Nick Whetstone - TNT UK
Reviewed: October, 2013

A little while back I reviewed a remarkable USB DAC from iFi, remarkable in that it was such a step forward in sound quality from previous USB DACs. It turns out that the iDAC is just part of a range of products that look very similar, and are designed to work together. In this review I'll take a look at the iTube, a valve pre amp that is so much more than just another amplification stage, and the Gemini D-H, iFi's replacement for a standard USB cable.

I'll start with the iTube that came to me in the same very classy packaging as the iDAC had, and looks very similar to its stable mate. It's dimensions are (H x W x D): 28mm x 68mm x 158mm). On the front panel is a volume control knob and two switches. On the rear panel are two pairs of RCA (phono) sockets for analogue input and output. With very little space on the these end panels, the power input socket is moved to a side panel, with the power supplied from a wallwart PSU.

[iFi iTube pre amp/buffer preset DIP switches] iFi liken the iTube to a Swiss Army pen knife, ie a collection of tools in a small package, and that's a good analogy. It's more than a simple pre amplifier or buffer, although it will perform that function very well using a ( General Electric 5670 based) valve circuit almost miraculously hidden inside it's small case. If you require the gain of a preamp, the iTube can be configured to give gain but if you don't need any then it will also function as a buffer, ie zero gain. You choose how it acts by setting DIP switches on the underside of the case. In buffer mode the input impedance is 1 M ohm, and in preamp mode 100K, both high enough to ensure that there is never an impedance mismatch with whatever is plugged into it. That's a pretty versatile piece of kit but there's more!

The iTube contains two additional switchable circuits. One, called the Digital Antidote Plus® is claimed to "re-equalise harsh, "ringing" digital sources which causes listening fatigue". The second, called the The 3D HolographicSound® system is claimed to provide a more three dimensional effect to the music, and is based on an idea put forward by Alan Blumlein way back in the 1930's. It's difficult not to notice the irony of a piece of equipment designed to work in 21^st century digital systems that returns to valves and 1930's theory for much of its design, but in hi-fi, we know that much of the so-called older technology still works perfectly well. Anyway, it is claimed that the 3D HolographicSound® system will compensate for how we actually hear sound, and in doing so improve how we perceive the sound stage, and the various components, ie instruments in it.

The iTube also has an an analogue volume control for those that prefer to use one instead of the digital volume control in a computer source. However, if it isn't required, that volume control can be left out of circuit (by selecting buffer mode). Clearly a great deal of thought has gone into the design of the iTube to offer as much as possible but without putting too much unnecessary 'clutter' in the signal path. I hope that I have covered everything with this rather clever box of tricks, and you can read a fuller description of all this on iFi's site.

Of course, it's one thing to look clever, and another to be clever. As the old saying goes: 'he's a clever old cock but he can't lay eggs'. So how does the iTube actually perform? It made sense to team it up with the iFi iDAC for this review, although I also tried it with the Miniwatt n4, and an old CD player. I used a few different amplifiers, and both my own familiar MS Pageants and a pair of Alacrity Audio Caterthun 8's.

Where do I start with something like this? Well, overall, the iTube is a very transparent piece of hi-fi. Whether I was using it in pre amp mode, or buffer, or even when using the 'effects', the music remained clear, and for want of a better word, untainted. Having the volume control in circuit may have been very slightly noticeable but you would have to listen very hard. So don't worry that it may somehow do unpleasant things to the music, it doesn't in any way. I say that because when we go to such lengths to produce bit-perfect sound from the source, it may seem odd to place something in the audio chain that 'messes' with that signal. I can say that in none of the configurations that I tried did I feel that anything was awry.

[iFi iTube pre amp/buffer rear panel showing input and output sockets]

iFi talk of the philosophy of adding 'valve sound' to a system, and I personally go along with what they say. Adding valves generally makes music 'nicer' to listen to, and in some systems, eg using classT/class-D amplification I would say that a preceding valve stage is mandatory. I hadn't been using a valve stage between the iFi iDAC and Gainclone monoblocks and was undecided if the iTube made much difference. But with a Virtue Audio Sensation class-D amplifier, I clearly preferred the sound with the iTube acting as a valve buffer. I didn't really find the need for more gain but changed to the 6 db setting simply to hear if there was any difference apart from how loud the system would play. Apart from my comment about the volume control, there was no audible difference in sound quality between the pre amp with gain, and buffer without.

Moving to the 3D settings, I started off with the selector switch in its middle position, ie the circuit is switched out. Moving the switch to the down position didn't result in any immediately noticeable change but after a while (and several instances of switching the circuit in and out) I did perceive what was going on. The sound stage is less compressed, particularly sounds from the lower end of the frequency range are better spread out. There were three effects resulting from this. First off I felt that the perceived 3D effect was increased. By that I don't mean that the sound stage was deeper, but each element within in was more 'rounded' than flat. Secondly, the instruments in the sound stage were spaced more widely apart. Thirdly, and this was more noticeable as I listened to more material, the drum kit in particular the bass drum became much more prominent, not in an imposing way but just so that it added more to the overall enjoyment of whatever I was listening too, and did give a more 'live' feel to the music too. It should also be said that the effect of the 3D circuit is more discernible as you turn up the volume.

I do have desktop speakers on my main computer system but they are the cheapo active type, so I set up an alternative system of a Bantam Audio class-T amp, and some small Pioneer speakers that I have had sitting around on my test bench for years. The sound quality from these speakers isn't great but the system, with the iTube of course, did enable me to experience what the 3d circuit does with near field listening. In this case, the 3D switch is set to the up position. Perhaps due to listening much closer to the speakers, the effect this time was immediately apparent. The sound stage got wider, the imaging was clearer, and the lower end was firmer, and slightly fuller. Again, all this benefit was not at the expense of transparency, or something sounding 'not quite right'.

Moving on to try the Digital Antidote Plus circuit (DAPC), I found that to be a lot harder to perceive any difference, and before I go further, I should state that it is designed to work primarily with SACD players, although it will work with any digital system. Said to remove digital harshness, this circuit is probably invaluable on lesser digital systems but I am finding these days that there is almost no harshness from a good system. The system (computer and hi-fi) that I was using at the time of testing this circuit ran off the excellent James Audio mains conditioner that itself removes a lot of glare from the sound. Reluctantly I swapped out the conditioner for a simple trailing mains lead with 6 sockets and powered up the same system again. Now I felt that the DAPC was making more of an improvement, although it's something that you probably wouldn't notice unless it was pointed out to you. In the hope of giving the DAPC a real test, I got out my old Philips CD723 CD player and connected that to the iTube. WOW - I hadn't listened to the CD723 for a long time but it made me realise how far digital playback has come in the last 15 years or so! Suffice to say that I wasn't tempted to get out a lot of my old CD's but it did show the DAPC to be working more effectively than it had done with a better digital source. In short, how much benefit the DAPC will provide will depend much on the source that it is used with, and the quality of your mains supply. But again, it did nothing negative so going back to the analogy of a Swiss Army penknife, it's a tool that you may not require but it is at least there if you need it in difference circumstances. However, as with the 3D circuit, the effect of the DAPC is much clearer as you increase the volume. I found it possible to turn the volume up (much) higher without that slightly edgy feeling. In other words, I could play much louder without it sounding uncomfortable (and for that reason I left the DAPC switched on all the time).

For me, the iTube 'does what it says on the tin'. The valve stage adds enjoyment to the listening experience, the music is simply more natural and relaxing to listen to. The 3D feature is something that I found myself leaving switched in because I liked the sound stage, and particularly the fuller bottom end, and more realism that it provided. The versatility is also welcome if like me you get to use a wide range of amplification and speakers, or you simply want to use the iTube in different systems. It worked faultlessly all through a very long auditioning process, and despite it's long list of features, was easy to set up and use, although it is one item where you should certainly read the instructions. I'm sure that there will be some purists scoffing at the idea of (and claims for) the Digital Antidote Plus® and the 3D HolographicSound® but the fact is they do work, and in my opinion improve the listening experience, the latter more so. All this makes the iTube fairly unique (at least at the time of writing this review) so I would say to anybody looking for an upgrade to their system, give the iTube a try, I am sure that you will be very pleasantly surprised, and at the price it's a lot of features for the outlay. One last point that shouldn't really need making but I will anyway: the iTube is very unlikely to make a poor hi-fi system sound good so if you have a problem with yours, remedy that first and then try it.

iFi Gemini D-H USB cable

Another USB cable?

Product name: Gemini USB cable. Manufacturer: iFi
Cost: 0.7 metre version 165 UK pounds; 1.5 metre version 235 UK pounds.
(Currency conversion)
(YMMV)

Reviewer: Nick Whetstone - TNT UK
Reviewed: October, 2013

Yes (or is that no?) I hear you saying - another USB cable? It seems that boutique USB cables will become the norm from companies producing upmarket USB DACs, so let's take a look, and listen to the one from iFi. (Lucio doesn't like cable reviews on TNT so I hope that I don't get into trouble with this one)

It's natural to compare the Gemini with the U-Craft USB cable from KingRex. Apart from the colours, they look much the same right down to the aluminium connectors. They both come beautifully packaged, and they both do the same job, ie separate the signal and power lines, deal with radio frequency interference (RFI), and facilitate the supply of power from another source such as a battery pack or separate power supply. One nice little bonus with the Gemini is that it comes with an adaptor so that the cable can not only be used with their own USB DAC (and others that use a type-B socket) but also those with a type-A plug, ie the "hiFace DAC or USB converter, Devilsound DAC, etc.

Comparing the Gemini to the U-Craft, the first real difference that I noticed was that the two separate conductors stay separate until the last RFI blocker that is adjacent to the USB connector that plugs into the DAC. The last metre of the U-Craft has both the separate conductors combined (back) into the same cable, something that I still don't understand. Again comparing the Gemini to the U-Craft, the cables are round in section, and quite flexible, making it much easier to place them where you want them, and less likely to dislodge what ever they are attached to. The machined aluminium alloy connectors are very similar to those on the U-Craft, and again are claimed to provide shielding as well as rigidity. In addition to the shielded connectors, the Gemini boasts not one but three "Custom designed adjustable triple RF silencers, providing the widest possible filter range without affecting the USB signal". Finally, "the Gemini cable adheres to the 90 ohm specification of the USB transmission protocol exhibiting just a 1% deviation from the 90 ohm impedance end to end (ie. connector + cable together)". As regards appearance, the Gemini looks a bit more 'grown up' compared to the rather glitzy look of the U-Craft but of course which looks more appealing is down to personal taste.

[iFi Gemini plugged into iDAC and thead supplied USB adapter.] In use the Gemini is certainly noticeably better than a bog standard USB cable, but as with the U-Craft, I couldn't honestly say that I found it significantly better than the Elijah Audio cable that I auditioned in this review of the hiFace converter. Of course it is a much better constructed cable with the RFI shielding, and perhaps if RFI was more of a problem in my home I may have heard a difference but I can only report honestly what I did hear. Another factor that may affect trials of this sort of equipment could be the excellent James Audio mains conditioner that I use in my auditions. Obviously the better a system is, and if it has better mains, it will sound better, the harder it is to get further improvement. So I went to some trouble and removed the mains conditioner from the system, and plugged everything into a standard mains distribution block, the sort that you can buy for a few pounds in a local hardware store. The glare that the conditioner removes was back, and now when I used the Gemini or Elijah Audio cables with a separate power supply, the improvement was more discernible. However, if I am totally honest, I still couldn't detect a difference between the Gemini and the Elijah Audio cable.

I'm not going to dismiss the Gemini. I felt that it is better designed than the U-Craft (in terms of the power and signal cables being kept separate almost until the end of the cable that goes into the DAC), and the cables are more flexible, and therefore user-friendly, and it's only 255 pounds here in the UK for the longer, 1.5 metre version that is comparable to the U-Craft that costs over 500 pounds, ie twice as much. The shorter, 0.7 metre version of the Gemini cost 165 pounds against the 66 pounds for the Elijah Audio cable (that is a bit shorter again) but the build quality is clearly superior, and it boasts the RFI shielding that the latter doesn't have. With respect to Elijah Audio, and I have been using their cable for many months now without a problem, it doesn't look as if it would survive as much handling as the Gemini. Certainly at the price of the shorter version (and why not just place your DAC nearer your computer source?) I am happy to recommend it. I see it like this: I have here a cheap watch that was given away as a bonus in a mail order sale. It keeps almost perfect time. A friend has his Rolex watch costing thousands of pounds, also keeping perfect time. Should we dismiss the Rolex simply on the grounds of its extra cost? No because a lot more has gone into the Rolex in terms of time and materials, and that's how I see the Gemini (much of which I understand is assembled by hand). Had it been the price of the U-Craft, I would not be recommending it, but considering the work that goes into making it, I felt that the price is fair.

I should just add that while using the Gemini, in conjunction with the Paul Hynes SR3-05 power supply, the iFi iDAC and iTube, and the Caterthun 8 speakers, I heard what I considered to be the best sounding hi-fi that I have heard to date in terms of detail, tone, and clarity. So the Gemini certainly wasn't letting the side down, and is probably one of those components of a hi-fi system that is more appreciated in a better system.