iFi iDAC & iUSBPower

iFi iDAC
Device Type: USB Digital to Analog Converter/Headphone amp
Input: USB Audio Class 2.0
Output: RCA (single-ended), minijack for headphone
Dimensions (L x W x H): 158 x 68 x 28mm
Weight: 193g (0.43lbs)
Price: $299.00

iFi iUSBPower
Device Type: USB Power Supply
Input: USB (Type B)
Output: USB (Type A) Power Only, USB (Type A) Power + Music
Dimensions (L x W x H): 158 x 68 x 28mm
Weight: 193g (0.43lbs)
Price: $199.00

Availability: through Authorized Dealers
Website: www.ifi-audio.com

iFi is an outgrowth of Abbington Music Research (AMR) "with trickle-down technology licensed from AMR and aimed primarily at the future, Computer Audio generation". We have two components under review from their Micro line—a USB DAC/Headphone amp and a USB power supply. For a combined price of $500, the iFi pair offers a lot of musical muscle for your money. The rest of the Micro line includes the iCan headphone amp ($249), and iPhono MM/MC phono preamp ($399).

iDAC (left) & iUSBPower

I was interested to know who iFi officially is so I asked Darren Censullo of Avatar Acoustic, iFi's distributor among others including AMR, Who is iFi?:

iFi is a subdivision of AMR (Abbingdon Music Research) and is a joint venture project with AMR and involving some very large non-audio manufacturing companies. AMR did all of the engineering and design work and is the face of iFi since they had the infrastructure to support the distribution of the products.

Let's focus on the iDAC first. The iDAC is an Asynchronous USB DAC that can handle up to 24/192 data employing the popular ESS Sabre DAC chipset. There's a USB input, RCA outputs, and a headphone minijack with associated volume control. The iDAC and iUSB Power's matching extruded aluminium chassis are nicely made and do not match their price, imo, looking as if they fit costlier components. They are relatively small, about the size of a deck and 3/4 of cards. Overall, a nice package.

I also asked Darren Censullo if he could provide more detail about the iDAC's circuit. Darren passed along my inquiry to AMR and here's Thorsten Loesch of AMR's response:

The DAC solution
After extensive listening tests iFi selected the ESS Sabre DAC with its built-in digital filter; as it offers excellent performance beyond the competitors. Atypically, we apply data to the ESS Chip directly, Bit-Perfect, without any manipulation, upsampling, extra filtering as we found the results of doing so of dubious utility.

One key to good sonics is the correct selection of passive components for the design, as they can have a very large impact on sound quality, much bigger than using different digital filters. At iFi we also use very low-noise and very high-speed regulators by Texas Instruments (selected for sound quality in extensive listening tests) for the DAC.

The USB solution
The USB circuitry and firmware are directly taken from the AMR DP-777. It is custom XMOS based design with custom firmware and completely supplied by AMR as a "turnkey" solution.

AMR's XMOS design dedicated an ultra-low noise regulator from Texas Instruments especially for the Clocks. Other individual power supplies cover the USB Receiver and the XMOS Processors core and input/output.

AMR's XMOS design extensively uses very low-noise regulators of the latest generation, not LM317 or AMS1117 equivalent generic 3-pin ones which tend to be 3 times or more noisier. Worse, the common 3-pin regulators have little high frequency noise rejection, at 1MHz the more modern types AMR employs have around 300 times greater noise suppression than the common 3-pin types.

The Clock solution
Most designs we evaluated either pass the clocks through the processor/FPGA or through additional selection logic, each of which will add more jitter to the clock than produced by even cheap clock crystals, thus negating much of the benefit of high-quality clocks.

With our design, the audio clock directly drives the ESS DAC Chip without any added circuitry, just around 1" of total PCB trace. This guarantees that this critical clock stage is of the highest quality.

The special design by AMR directly outputs the two audio clocks from the oscillators without ANY additional circuitry for selection or buffering, giving the best possible audio clock and uses high-grade, low-jitter crystal oscillators (the same clocks are used in AMR 77 and 777 equipment).


Signal to Noise Ratio:

Dynamic Range(-60dBFs):


Total Harmonic Distortion(THD):

Below measurement limit

Frequency Response:
3Kz to 33KHz + 0.1dB/0.3dB

Headphone section:

Output Power:

Signal to Noise Ratio:

Total Harmonic Distortion:


Output Impedance:(Zout):

Power Consumption:
< 2.5W

The iUSBPower is an ingenious device that's meant to sit in between any USB DAC and your computer and act as a filter against the grunge coming out of your computer and traveling through your USB cable. iFi also recommends using the iUSBPower in between your music serving external USB hard drive and computer as well as with the Squeezebox Touch. There's one USB input (type B connector) and two USB outputs (type A)—one for use with a standard USB cable, the other for use with iFi's upcoming optional Twin-Headed USB cable. There's an input for the included "ultra low noise power supply" and three status LEDs up top indicating power, IsoEarth engaged (or not), and USB connectivity. iFi includes a 21" USB cable with the iUSBPower.

iDAC (left) & iUSBPower

While I know there are all kinds of seemingly logical reasons why this kind of device should not be necessary, I have found that it is, more and less, depending on the DAC (I did not try it with an external USB drive because I don't use one. My music is all NAS-resident). How does the iUSBPower do what it claims it does? From iFi:

To create a USB power supply that is ultra-quiet is an engineering feat in its own right. We went several steps further. The Super Regulator technology encompasses; multi-stage and multi-order power purifying with filtering. We even commissioned a special, audio-grade USB power supply unit. The iUSB with an excellent voltage accuracy of 0.5% is even quieter than a 9V dry cell battery.
I have a 9V dry cell battery sitting on my desk and it is indeed, very quiet (that's powerful humor). The iUSBPower also employs an optional (with a switch) IsoEarth ground noise elimination system. Here's AMR's Vincent Luke on why I did not hear any change with IsoEarth engaged with my MacBook Pro:
This feature [IsoEarth] works by breaking earth/ground loops that can occur in and around the computer itself or other items in the system (e.g. USB Hard Drives). This can lead to audible hum or buzz or if it is not audible, may degrade sound quality.

As your MacBook's power supply does not have an Earth Connection on the power supply this particular feature will not provide any benefit in your system (the earth connection giveaway is if the 'power brick' has 2 or 3-pins). Desktops being of the 3-pin variety are almost all certainly earthed.

Furthermore, from our testing, even a computer with no earth can benefit if the external HDD connected to it is earthed. We came across one such instance where a WD USB MyBook (earthed) connected to a MacBook (not earthed) with the addition of the iUSB removed severe levels of hum.

The i's Have It!
For the majority of this review I listened to the iDAC with the iUSBPower because it sounds better that way. The iUSBPower makes a clear and distinct improvement in low level detail retrieval, bass response, overall clarity, and the perceived soundstage both in terms of its size and solidity. These traits varied from DAC to DAC but with the iDAC I'd say the iUBPower is pretty much a you are going to want this kinda deal. It offers clear and easily heard improvements. I only hope I've made this as clear.

While we're on the iUSBPower, I would also say that it does not alter the overall sonic signature of the DAC it's being used in conjunction with, rather it simply improves the qualities I just described. I found this to be the case with the AudioQuest Dragonfly and to much lesser extent the Resonessence Labs Concero. I would say that a very general rule would be if your DAC is USB-bus powered, the iFi iUSBPower is certainly worth a try. For self-powered DACs it may also offer improvements depending on how well, or poorly, your DAC filters the USB input. For $199 its worth a try, imo.

The duo of iFi iDAC / iUSBPower offer up a big, fat, rich and rewarding sound. It's not overly dark, rather I find it to be balanced very much near my 'just right' center. While there's plenty of detail, there is not an emphasis on the leading edge but there is a boatload of attention paid to the midrange, timbre and decay. Something like the Concero DAC offers up a more resolute sound with an emphasis on clarity and pace. The iFi duo add more meat to the sonic bones. On the down side, the iFi duo does not provide the last word in bass impact or detail retrieval for complex music. I'm not saying the sound is muddy, just that I've heard more bass and more resolution from other DACs. The tradeoff is a solid, mid-range rich presentation. Something you can sink your teeth into.

that blue USB cable comes with the iUSBPower

The iFi iDAC retains this overall character without the iUSBPower and it is a very fun and engaging DAC to listen to in its own right. I would say that it begins to lean toward the darker side of things without the iUSBPower but not so much that you'd really mind unless you are a detail/edge/upper frequency all fretboard and fingernails freak. Not that there's anything wrong with that. Bass is also fat if a tad loose (this improves with the iUSBPower) and the iDACs presentation is very forgiving of recording quality where even less than stellar CD-quality music is completely enjoyable. Well-recorded music is served up very nicely, too.

The problem with better in hi-fi land is once you hear it you continue to want it so once I listened to the iDAC with the iUSBPower it stayed in. But if your budget for a DAC maxes out at $300, you can certainly enjoy what the iDAC has to offer and know, for certain, that you can always get better once you save up the $199 for iUSBPower.

The iDAC's headphone amplifier drove my Audio Technica ATH-W1000 with ease and as is usually the case, the sonic traits described above traveled down to the headphones as well. I was a bit more aware of sparkle and strum with headphones, but I'd attribute this to my setup as much as to the iFi iDAC. Again the sound was rich, full and generally fun to listen to.

Another interesting application for the iFi dynamic duo is in conjunction with Apple's Camera Connection Kit ($29) and all together this team will turn your iPad into a 24/192 music serving machine (see link for details on the iPad software setup). Just connect the CCK to your iPad, the iUSBPower provides the necessary (clean) power, connect that to your iPad and iDAC, and the iDAC to your powered speakers or hi-fi and you are good to go. Note: the iDAC on its own draws too much power for the iPad so you either have to use it with the iUSBPower or a powered USB hub. Also note that the iUSBPower will work with other DACs in this same scenario.

AMR's Vincent Luke also mentioned that they have found the iUSBPower enhances the performance of the ever-popular Squeezebox Touch. This setup requires a USB to DC cable that now comes standard with the iUSBPower. Existing customers will receive this cable at no charge. My review loaner did not include this cable so I will report on its use with my Squeezebox Touch in a follow-up review.

something exactly like Julia Holter's stunning Exstasis sounds particularly lovely through the iFi Duo with all of those harmonies and reverb tails trailing off into space (yours)

Choice of Voice
This was another review where it was mostly all fun from the first to the last notes played through the iFi duo. Like the Halide DAC HD ($495), Wadia 121 ($1,299), and Resonessence Labs Invicta ($3,995), I enjoyed every musical minute. For those readers-between-the-lines, I'm not saying the iFi duo is the equal of these more expensive DACs. Rather I am saying that I enjoyed listening to the iFi duo and found nothing to distract me from listening for pleasure. Its faults very nicely balance with its strengths. One sure sign this is the case is when you can't wait to listen to that new download you bought as opposed to you can't wait to hear what that new download you bought sounds like. While you will get more resolution and bass impact with the Wadia (as well as a preamp), and improved detail retrieval for even the most complex music along with a smoother and more natural presentation from the Invicta (and a preamp), you could very well enjoy listening to the iFi duo as much as I did.

With products like the Audioquest Dragonfly ($249), Resonessence Labs Concero ($600), Halide DAC HD ($495), and the iFi iDAC and iUSBPower, music lovers have more choices than ever for affordable, well made, and very musical sounding DACs to make their computers sing. The choice between these DACs comes down to the voice you most enjoy and only your ears know the answer to that question.

Associated Equipment

Also on hand and in use during the iDAC and iUSBPower review: Mytek Stereo 192-DSD DAC, Resonessence Labs Concero, Chordette QuteHD DAC, Cambridge Audio StreamMagic 6

Bob Walters's picture

I've been listening to more than a few "affordable" DACs in preparation for a Bay Area Audiophile Society meeting next week.

The iFi pair distinguished itself during my comparisons for many of the reasons that you point out. It's a nice step-up from the Dragonfly (which we'll also feature).

The competent (blue) USB cables that the units ship with are a nice bonus.

Kinda makes me want to try the AMR 777.


rolf_17's picture

Hi Michael,

Btw I really enjoy reading your reviews.


Would you recommend the iDac on its own merits without the iUsb in the path ?

This will be my first dac purchase, still waiting to get it from stereodesk.

Some background, I have ripped my CD collection to flac with EAC and accuraterip. 

From what I can tell they are mostly 16 bit files with a 44Khz sample rate, I suspect this was their native PCM settings.

I mainly listen to music through AKG701 headphones and play 1 computer game through my XFi sound card which to me sounds excellent already.

But based on all the hype surrounding how much better things can sound with a external DAC I have decided to give it a go. I purchased the iDac without the iUsb.




bluedoor's picture

Hello Michael,

Have you tried the iFi usb with the Chord Qute?

The improvments justity the purchase of one of this thing?