Disclaimer: A big thank you to Ifi for providing me with the iUSB Power to review.
If you're a regular visitor to this blog you'll have noticed a few devices from Ifi Audio on here recently. I've been lucky enough to play with almost their entire catalogue, which is especially great considering they work so well together. The iUSB will be the last of the Micro Ifi devices featured, but as you may have seen on the Head-Fi meet article, there are some even smaller portable units on their way that look very exciting indeed.
The iUSB's purpose is to purify the power supply in sensitive audio equipment (typically USB DACs), removing troublesome noise from the equation. It's design to work with any USB DAC, not just Ifi's own iDAC, but it can also be used in conjunction with the Ifi Gemini for even better results. The fact that these two items are bundled together shows that Ifi sees a benefit to this combination and they are not simply alternatives to the same problem.
I found the Gemini cable helped clean up the sound quality somewhat, but the difference made by the iUSB was more noticeable. The effect with the iUSB in place is one of less grain and one that sounds cleaner and more clear. It also felt easier to sense finer details and separation seemed better. This will be obvious to some, but also like the Gemini (or any cable upgrade), this is not the same difference as adding a good DAC and amplifier, but it can make an appreciable difference. I say 'can' because it depends on a great many factors. One factor to complicate matters is the background noise of the environment you're listening in, but the two main factors are the power of your source and the DAC being used, the latter because higher end DACs can also use various methods to purify power/signals internally too.
The iUSB is going to be more effective with desktops computers where power comes from the mains and there's so much of it being thrown around that's poorly isolated. Although laptops are much less susceptible to these kind of problems while running purely off of a battery, some issues can still occur when they're charging. Desktop power supply units (PSUs) vary greatly in cost. Some come free with a £30 case and others cost up to £200 on their own. Obviously the quality of their power will vary too, but none are built with high-end audio equipment in mind. You might think that the low voltage (5v) power accompanying a USB cable is innocuous, but the problem is it's not isolated from the rest of the system. This is where the iUSB steps in to save the day. As most people will know battery powered systems suffer from less noise, but the iUSB's noise output is rated even lower than a typical 9v battery, now that's an impressive boast!
SET UP
The iUSB used in conjunction with the Gemini cable can improve things yet further. Although both the Gemini and iUSB are made to assure the power interferes with the audio processing as little as possible, they go about it in quite a different way. The iUSB aims to purify the power as much as possible, whereas the Gemini tries to solve contamination issue by avoiding it entirely. Depending on how you look at this (or what equipment you have) you can use these two methods in different orders. Ifi recommend the Gemini be used post iUSB for best results, but the way I see it both have their merits.
- Computer > other USB cable > iUSB > Gemini > USB DAC
This makes sense in my head because it keeps the potentially dirty power away from the data until it's re-combined after purification. Of course you're welcome to use it either way around if you so wish. It's nice that the iUSB allows this flexibility, by having the second USB output provide data and power (they will be combined unless you're using the Gemini cable).
Barring cost there's also nothing to stop you using two Gemini cables (one on either side of the iUSB). Even with my new found appreciation of power purification, it's rather difficult to justify this. Since they already work so well apart and together, I find it hard to believe there's much more room for improvement, but to be fair I haven't had the chances to try it yet (since I have only one Gemini here). Ifi did confirm that this would provide the best potential results, so if you're able to afford it by all means give it a go.
BUILD
The iUSB chassis' build and design is consistent with all of the other Ifi Audio Micro devices, so when used with the iDAC and/or iTube etc. you can happily stack them. Ifi will soon be making available a stand to fit up to four Micro devices together. From seeing this at the Head-Fi meet I can say it certainly makes them neater and sexier.
Like the iTube and iCAN the iUSB uses the same 9v adaptor to provide it's power. Unlike the iTube the power socket of is on the back of the unit, which keeps it neatly out of the way, I just wish all of the USB sockets were also on the back for the same reason.
The iUSB is a power purification device that can used with any USB DAC. It makes even more sense when used to power USB DACs that are combined with headphone amplifiers because that power goes on to directly amplify your sound. Further versatility can be achieved when combining this with the Ifi Gemini cable, which can be used at either end of the iUSB, but that's not to say this isn't a compelling product on it's own.
Compared to the Gemini I think that the iUSB provides an even stronger benefit in cleaning and improving audio in most cases, even if it's a bit more fiddly to add to some systems. For example: a USB powered DAC and headphone amplifier used with a laptop is very convenient (as it doesn't require any power cables), adding the iUSB to the equation destroys that simplicity somewhat. Being powered the iUSB is obviously reserve for desktop systems and that's no bad thing, it's actually nice that between this and the Gemini there are options for either scenario.
Something like the iUSB is not as important as choosing the right DAC and amplifier, it won't fundamentally change their sound, but it can purify and hone it to perfection. I noticed and appreciated the difference made by adding it to my desktop systems. It might not be cheap, but this kind of quality never is.
Dell Vosto Laptop, Custom Desktop PC, Schiit PYST, Ifi iDAC, Ifi iTube, Ifi iCAN, Denon AH-D7000, Hifiman HE-500, SoundMAGIC HP200, Mr. Speakers Mad Dog, Beyerdynamic DT770 Pro Limited Edition, Sennheiser Amperior
