Simply put ifi nano iUSB3.0 is an active (i.e.: autonomously powered) device which makes communication much better between a digital music player (e.g. a laptop, a multimedia server, etc) and a USB-connected and possibly USB-powered DAC or DAC-AMP.
Nano iUSB3.0 does 3 main things:
1 – Provides clean(er) power
Nano iUSB3.0 forwards the clean(er) power coming from its own power supply to the downstream DAC / DAC-AMP, which will stop receiving the “dirti(er)” power coming from the host’s non-audio-grade PS, furtherly dirtied by host’s internal circuitery and activities.
Nano iUSB3.0 comes bundled with ifi’s iPower, a good quality
audio-grade SMPS (Switched-Mode Power Supply). It can be furtherly upgraded adopting an even better PS e.g. ifi’s own
iPowerX (an even more sophisticated and cleaner SMPS) or any suitable third party SMPS a Linear PS if need be. Mind you: a Linear PS may cost a few times the price of your DAC

That said, ifi themselves warn that nano iUSB3.0 already does some great job at cleansing the power it passes along that it is quite resilient to variations on the upstream PS. Read: an even better PS will indeed improve output, but probably less than expected.
2 – Actively cancels (a lot of) noise
Nano iUSB3.0 features “Active Noise Cancellation”. The concept is quite similar to that applied on Balanced analog lines: a second signal is generated identical to that of the incoming electrical noise, but in the opposite phase; the two signals are then “summed” together, which cancels the noise leaving the “good” part intact.
According to better engineers than myself this approach is significantly better than the cheaper “passive filtering” alternative: passive filters remove hi freq interference only, active filtering act on lower frequencies too. According to ifi, this technology only inside iUSB reduces the noise floor by > 40dB (> 100x).
Of course having less noise to start with - e.g. from the power suppy - is always good but even when the power supply is not so great, nano iUSB3.0 (see point 1 above) "cleanses" the signal significantly for us.
3 – “Fixes” the USB data stream
Nano iUSB3.0 re-clocks, re-generates and re-balances the USB data signal. What does that mean?
The key thing to understand here is preliminary: unlike what happens when moving digital data (e.g. a MS Word file) between a pc and a hd, or between a pc and another pc,
precise timing is a relevant factor when digital audio data (e.g. a FLAC song file) is streamed between a pc or similar “host” and a digital input audio device “client”.
- Any USB communication requires some sort of “timing” (called “clock”). This is typically offered by the Host (in our case, the PC). Guess what: the host’s clock accuracy is “good enough” for digital data communication, but easily gest “too inaccurate” for the sake of digital audio communication. Nano iUSB3.0 reverses the Host/Client clock relation : it uses its own internal clock (Re-Clocks) instead of the host generated one, thus removing all undesidered incoming frequency variations (“jitter”) and other stuff.
- The presence of possible DC offsets between the two ends of an USB communication channel - e.g. due to ground loops, or to EMI - is another potential source of inconsistencies. Nano iUSB3.0 corrects - Re-Balances - DC level differences at the two ends of the USB line to prevent these issues..
- If there is “noise” (interference or whatever) down a USB line during a transfer between two digital data devices, then some digital data packets will get disrupted, and a retransmission of those packets is seamlessly requested and executed between the devices. All this is so automatic and smooth that we don’t perceive any issue even in a relatively (electrically) noisy environment e.g. while writing data from our PC to a USB-HD: worst case, due to retransmissions the file transfer speed will be a tad slower – but data (i.e. our actual file contents) will always be perfect at the end.
If the receiving device is an audio digital device, instead, a retransmission for error correction screws timing up (much more than clock jitter by the way). Accurate data will still reach the destination, but not “on time”. On digital audio, this *is* a problem. Nano iUSB3.0 Re-Generates the entire USB data stream, cutting the rope with host-incoming packet noise and providing the downstream DAC / DAC-AMP with a “fresh clean renewed”, correctly timed stream. Very simplistically put, it's much like it buffers the incoming packets just a bit, and supplies them to the output USB port (where the DAC is plugged) following its own "precise" timing.
Last but not least: Nano iUSB3.0 does all this at USB3 speed (5 Gbps), which means it can process on-the-fly digital data streams up to the maximum resolutions currently supported by TOTL DACs.
So much for the technology.
But does it work?
Hell yeah !
Very simply, I started putting nano iUSB 3.0 up in between my laptop and my USB-powered dongles: a Meizu HIFI DAC Pro - cheap but wuite nice in its category - as a first case, and a quite high-class Apogee Groove as a second case.
As test IEMs I used two kinda “reference” models – “reference” for my ears, at least: final E3000 and TIN T4.
The improvement when listening to Meizu HDP is nothing less than
huge.
The difference is very apparent on Apogee Groove too, while the delta is smaller as expected: Groove in facts already incorporates high-end (for its class and size) power cleansing technology, so nano iUSB3.0 impact is “mainly” about USB data stream “fixing”.
The overall sound in both cases is
evidently clearer. The difference is totally apparent on Meizu, less gigantic on Groove, but still very much there. Low tones are where the effect is more perceivable (ofc): back instruments and vocals suddenly gain better readability.
Listening via Meizu to a well mastered song with “silent moments” on one channel I would normally say such silence is “quite silent”. Then I plug nano iUSB3.0… and I find out that such supposed “silence” did in fact have “some SPL”, litreally as in “pressure felt on the timpanus”, which is now
gone.
Via Groove sans nano iUSB3.0 in the middle, those same “silent moments” are nearly on par with those reproduced by Meizu+nano iUSB3.0, while stacking nano iUSB3.0 I perceive further de-pressure, and some very faint background sounds (e.g. a player moving) get audible, or more audible, which were covered before.
Powering Groove via nano iUSB3.0 generates a whiff more of SPL accross all frequencies, whilst perceivably
reducing the high/low tones gap. In more vulgar words this means that without iUSB3.0 a song lead vocals and instruments are presented by Groove at (say) SPL=10, and back guitars at SPL=5, while by adding iUSB3.0 I will have front lines at 10.5 and back lines at 6. That is: everything is a little bit louder, but low tones gain more loudness than high ones and this of course grants
further clarity and detail to back-line voices.
The effect on
bass frequencies is better control and texture. Again, on Meizu the difference is nothing less than huge. On the Groove, which is already making masterful bass control a main cipher of its art, this equates into further bass texture – of which I’ll always be thirsty anyway.
On
trebles significant more crystallinity is offered. On some tracks, and on bright-leaning drivers this is even more apparent and may lapse into an unforgiving output (the IEM tuner’s art will show here…
if some has been applied, that is…).
Soundstage: improves not much in term of size rather in terms
spatiality: E3000 being already a blessed IEM on that respect, it now allows me to better guess the room size / shape. Sound is more
“coherently around me”.
Imaging: not only instrument positioning is furtherly palatable in a “more clearly lit” stage, as it sounds logical, but – less expectedly at least by me – some instruments also appear
better reciprocally spaced.
OK, it works. Do I (or you) need it ?
Ah well, it depends – in less then a thousand words – from the current status of your stack. And pockets!
I have zero practical experience with high end systems, so “by logic” (yet not by experience) I would tend to believe that you will need it
less (if at all) if
- Your DAC is already self-powered (and you already adopt an at least decent SMPS), and
- Your DAC already includes competent GND-managenement and power filtering features, and
- Your DAC already features key noise-dampening features e.g. USB-line jitter removal (reclocking), etc etc
On the contrary – and by direct expericence – will need nano iUSB3.0, or “part of it”, if (like me)
- Your DAC is host-powered (i.e., if it gets powered via the USB cable connected to the PC, and cannot accept power from a separate port), and/or
- Your DAC is non-pro class (not even low-end-pro-class), and lacks all or most forms of USB-noise prevention / suppression features
My reference DAC being Apogee Groove, I check the first one only of these latter two bullets big time: Groove takes power from my Laptop’s “dirty” line. A “cleaning” there is certainly welcome.
At the same time, as mentioned above Groove already incorporates quite a lot of input data noise control, which makes the second bullet point a lesser priority at least.
In terms of minmaxing my best option would have
probably been fixing the USB data line “purification” part initially, by means of an
iPurifier3 , and add a better PS part later (e.g. by means of
ifi iDefender3.0 +
ifi iPower).
The reason why I got a nano iUSB3.0 (incorporating the features of iDefender3 + iPower + iPurifier3 + some minor other stuff) has just one honest reason:
luck. The "nano" package having recently been discountinued by ifi in favour of the dual-sized (and dual-priced!)
micro iUSB3.0, this triggered a stock clearance sale from my local disty whereby I could harpoon a nano iUSB3.0 for less than the regular price of an iDefender + iPower. How could I not get that?
Micro iUSB3.0 is the current incarnation of the device. It apparently does the exact same job, the exact same way, but allows for
two USB downsteam devices to be connected at the same time, for something like twice the previous nano price. I don't want to argue on ifi's marketing choices ofc but this in my opinion leaves the market orphan of a fantastic €200-ish most-in-one-solution like nano iUSB3.0 used to be.