This review has taken me much longer than average to get written out, and the reasons, I think, will be evident through reading it. This product is absolutely jam packed with features, and every single one is precisely, nigh-perfectly, executed. I give massive props to iFi for managing to put out something as rock-solid as this, given how new they are as a company. I think that this is phenomenal introduction to their "Pro" line, and I am very excited to see what else they put out under that title.
Figuring out how to structure this review was as much an issue to overcome as sussing out exactly what I was going to include in it, but I hope that the structure below is conducive to understanding and legibility.
Starting at the basic: the design of this amp. As shown in pictures, it's understated, but still attractive. The venting on the top and sides is as much a design choice as it is purpose-built. The two NOS General Electric 5670 tubes that are used in the tube section of this amplifier put off a lot of heat, and it needs to go somewhere. Additionally, the Class-A solid-state section can independently put out quite a bit of heat on its own, although no where near as much as the tubes.
On the top, there is a magnifying/looking glass that very attractively displays the tubes used in the tube section, and watching them warm up, beginning to glow, is a pleasant experience in-and-of-itself.
While we're on the topic of design, I'd like to point out a feature that I expected to just be an extra, that I turned out to absolutely adore. Included is a remote. It controls the volume, and there is a motor in the potentiometer that physically moves the knob when you tell it to. However much I expected to use this infrequently, I quickly realized that there isn't a comparable feeling to lounging back in a reclining chair, with a nice pair of headphones, controlling your library from a mobile app, and watching the volume knob glide into position at your whim. For anyone who has never tried this, I very highly recommend it. It's a singular experience.
There are a number of switches and buttons on the front of the amplifier that control a variety of functions. Leftmost is a button that simply controls power. Moving from left to right, next is three-position sliding switch that controls the section that the amp uses (Solid-State, Tube, and Tube+). As the user switches between these positions, a light on the front behind the "Pro" under the iFi logo on the upper-left side changes from white (Solid-State) to yellow (Tube) to green (Tube+). The last switcher, which is rightmost, switches between the gain stages (+0 dB, +9 dB, and +18 dB).
I'd like to talk about inputs and outputs next, because there are a lot of them. In terms of the inputs, there are the following: three pairs of unbalanced RCA inputs, along with a pair of 3-pin differential XLR inputs, all on the back. These are controllable by the selection knob on the left of the front fascia of the amplifier. There are two options for line-out, also on the back: a pair of unbalanced RCA outs and a pair of 3-pin differential XLR outs. Now to the front outputs. There are more options here than anyone could ever possibly need. There are a pair of 3-pin differential XLR outs which also function as a pair of 1/4" balanced outs, a single 4-pin balanced XLR, a single-end TRS 1/8" jack, and a balanced TRRS 1/8" jack, all on the front fascia. That is definitely the most that I've seen on a prosumer product, but, as seen in the pictures, the design is symmetrical, which keeps the front from looking too busy, thankfully.
And finally, in this section, are the two remaining ports on the back, excluding power. One is a connector that allows connection to an upcoming energizer for electrostatic headphones. Unavailable at the time of this review, I was obviously unable to review the actual device, but the future-proofing that iFi has done for this product stuns me. The other is a power pass-through for the same device, to my knowledge.
I'd like to point something out that I'll reiterate in my conclusion: including the coming energizer, this amplifier can power anything on the market. Since I have yet to mention it, the maximum power that it can output is not 5 watts, not 10. Fourteen watts. That's no typo, this amplifier can put fourteen watts into a 16 Ω load, through either balanced or single-ended outputs. That will explode any headphone currently on the market that I can think of, likely including the nigh-impossible to drive HiFiMan HE-6. This is a one-size-fits-literally-all solution for headphones of every kind.
Design, Part 2
Now I'd like to move onto the technical side of the amps design. What interested me particularly, before I had even received the amplifier, was that this is not a solid-state tube hybrid amp like the majority of implementations that I've seen. It, fundamentally, is a fully balanced, Class-A solid-state amplifier that you can switch to be a fully balanced, tube amplifier. The circuitry is completely separated on the board, and (with a ~30 second delay from SS to tube and ~10 second delay from tube to SS) you can switch in real-time between the two, with a bonus "Tube+" mode that I will tackle later in this review. iFi discusses this in their information page, stating the following:
...and just as important is the circuit design. Unlike other headphone amplifiers that have the same circuit and just switch in/out the tube section, the Pro iCAN is the very first of its kind that has two individual input circuits – one tube and one Solid-State. This results in the best sonics of both worlds because the signal path is the shortest and there is no compromise to ‘shoe horn’ the tubes into an already existing solid-state circuit.
I quoted them as I believe they have explained it more concisely and accurately than I could have myself.
Speaking of separation, I'd like to momentarily discuss another element of the architecture of this amplifier. Unlike many "balanced" amplifiers which use a single-ended internal architecture, this amplifier uses a fully balanced circuit from input to output, with no exception. This is discussed in more detail on iFi's page for this amplifier (linked here), but I wanted to include their diagrams below to give a better sense of what that means in terms of the design of the amplifier.
Now that the introductions are done, we move to what actually matters, in regards to an amplifier.
iFi states that total harmonic distortion in the solid-state section is ≤0.0015% for balanced and ≤0.005% for single-ended. Now these are not HP-1 numbers, but these are much more than satisfactory for virtually any consumer in the market. I noticed no odd distortion, artifacts of amplification, nor any general unpleasantness. It absolutely and competently does the job of a solid-state amplifier, and offers almost unrivaled diversity and power.
I will never comment on the "sound signature" of any solid-state amplifier, as the electrical aspects of those claims are dubious at best and fraudulent at worst. It cleanly and correctly amplifies the given signal and reports it through the headphones to the user with faithfulness to source. This is the most I could ask from any solid-state amplifier, and it delivers.
The tubes they selected were an apt choice, in my opinion. Emphasizing the harmonics, they offer a warmer, slightly gooier sound than the solid-state section does. The fully balanced employment is a benefit for those who take advantage of it, and, as discussed above, the architecture of the amplifier is actually fully balanced.
I found that on bass anemic and overly fast-paced headphones, when I wanted a warmer, more full-bodied sound, the tube section offered what I requested. It doesn't stray to the world of imprecise or sloppy, only adding warmth and depth to music that may have lacked it before, as a result of the headphones used at the time.
This stage is interesting. iFi states that this section reduces overall loop-gain, reducing negative feedback, and emphasizing even more than already the harmonics, particularly second order. The effect of this is to essentially make the amplifier perform with more tube sound, however imprecise that sounds. Warmer, with more body, I spent a lot of time in this stage when I wanted to just listen to music, without a thought to analysis.
I think this inclusion is most definitely warranted, as it offers an increased level of musicality, even from the tube section. This especially applies to those headphones that may lack musicality when used with a very clinical, clean amplifier.
This is an implementation of the same ASP that they offered in their Micro iDSD Black Label. However, this implementation offers much more control than the Micro iDSD did. There are four positions to the knob, which is located next to the input selection knob on the left side of the front fascia. The first is off, next being a 12 dB boost below 10 Hz, the third being a 12 dB boost below 20 Hz, and the last being a 12 dB boost below 40 Hz.
I enjoyed this feature on the Micro iDSD, and I've enjoyed it more on this, as it offers more control of what is boosted. This is unlike any DSP bass boost, as it introduces near no distortion in the bass that it emphasizes, and is tremendously clean. It turned the Sennheiser HD 700, a fairly bass anemic headphone, and turned it into something that I think at which a basshead wouldn't necessarily up-turn their nose.
3D Holographic Sound
This is, again, an implementation of the same ASP that was present in the Micro iDSD Black Label. Also similar to the XBass implementation, it offers much more refined control. iFi states on their website that the four states of the knob, to the left of the volume knob on the right of the front fascia, are as follows: off, simulating a 30° loudspeaker angle, simulating a 60° loudspeaker angle, and simulating a 90° loudspeaker angle.
I wouldn't go so far as to say that it exactly replicates loudspeakers at the listed angles, but it certainly does a more than adequate job of increasing the perceived space within a given recording, without adding distortion or other unpleasantness. Oftentimes, I've found that in recordings where the vocal line seems fuzzy or unfocused, it served to better center and clarify that line.
I found myself using the XBass setting more than I did this option, but when I did use it, it almost always served to change the sound in the way that I was looking for.
Where I have been verbose in the rest of this review, I will try my hardest to be concise here. What I have found from my experience over the past month with this amplifier is as follows: this amp has everything that I could think to look for as a consumer. Incredible power? Check. An obscene number of inputs and outputs? Check. Cleanliness in its solid-state section, control and body in its tube section? Check. A fully, truly balanced design? Check. An extra tube option that offers more "tube-yness"? Check. Two great ASP implementations? Check, with more control than in their previous attempts. The option to attach an electrostatic energizer? Check. And finally, a remote control? Check.
The funny part, to me, is that the list I just made still occludes many of the features of this amplifier that I covered in this review. As a reviewer, this is not necessarily the list of features that I look for. What I look for is the absolute lowest distortion, high enough power, and balanced and unbalanced inputs and outputs, which is why I purchased the Neurochrome HP-1.
However, and more importantly, if/when I move from reviewing into simply listening, unless something monumental and groundbreaking enters the market, this is undoubtedly the amplifier that I would choose. I apologize to those reading if this comes off as fanaticism, because the simple reality after having used this amplifier for a month is that, from a consumer's perspective, this amplifier checks every single box that I could think of. I will be very sad to have to box this up and ship it back to iFi.
This product was provided to me for review by iFi. I am not being paid by anyone to write this review, to endorse the product reviewed, or for the content that I put in the review.
The signal for this amp was provided by a JDS Labs OL DAC, fed by USB from my computer.
I have had this product for about a month, and have used it for considerably more than 100 hours, but I stopped keeping track after that metric.