Solid State Home Headphone Amplifier Reviews

iFi Pro iCan Headphone Amplifier ($1699)
Let's say you've been enjoying the headphone scene for a while now. You've built up a sizable collection of cans and you'd really like to get the most from them. You know your current amp just doesn't bring out the full capabilities of your collection—you've set aside some money and finally feel ready moving up to a high-end model. But how to proceed?

The sensible part of you knows the best course of action is to find a good solid-state amplifier capable of doing justice to your entire collection. A neutral, straight-forward device with plenty of power for driving anything you might throw at it. But there's also that nagging voice inside, drawing you towards the sweet coloration of a mellifluous tube amp. Neutrality and accuracy is overrated, isn't it? Despite your indecision, you absolutely refuse to run more than one amp in your setup—maybe your source doesn't have enough outputs to support multiple devices, or perhaps there's just no room for another device. Either way, and despite your conflicting desires, you can only have a single amplifier.

What to do?

iFi Audio claims to have the answer in the form of their Pro iCan, a powerful $1,699 headphone amp with loads of sound tweaking features, most notably the ability to run in tube or solid-state modes. That aspect, plus several others, make it a pretty unique entry on the upper tier of headphone amplification.

Let's back up a bit and talk about the company behind the device. If you aren't familar, iFi is a relative newcomer who has made a big splash with their compact DACs, headphone amps, and power filtration products. Their first release, the $299 iDAC, earned a very respectable Stereophile Class B rating a few years back, and the praise hasn't let up since. After leaving a trail of positive reviews all over the web, most of which compliment iFi's formula of delivering high performance per dollar, the company now looks to move upmarket with their Pro series.

At time of writing there exists but a single model—the Pro iCan. In the works is a matching Pro series DAC as well as a very interesting add-on piece allowing the Pro iCan to power electrostatic headphones. As far as I can tell it's a transformer box which accepts signals from speaker amplifiers (just like the classic Stax SRD boxes, and the more recent Woo Audio WEE) or from the Pro iCan via proprietary connector. It then spits out a signal capable of driving electrostatic headphones. Interesting. I wish that had been available so I could try it out along with the Pro iCan, but it doesn't appear to be quite ready at this point.

Despite moving up-market, iFi hasn't completely lost their focus on value. The Pro iCan aims to compete with the best headphone amps on the market, while undercutting them in terms of pricing. Top headphone amps these days can hit $3-4K without breaking a sweat, so the $1,699 Pro iCan could theoretically be seen as a bargain.... assuming it performs on that same level.

Design
Despite its small stature—just 8.5 inches wide, 7.5 deep, and 2.5 tall—there's a ton of functionality packed into this thing. The rear panel sports a total of four inputs; three RCA and one XLR. That's more than you'll find on the majority of competing headphone amps. The idea here is that the Pro iCan doubles as a preamp, complete with simplistic remote for volume control. Not sure how useful the preamp function is for most headphone lovers but as a reviewer testing numerous devices I found it quite handy.

Up front, iFi provides an array of headphone jacks which is among the most comprehensive you'll find anywhere. For balanced output, we get the standard 4-pin XLR along with dual 3-pin XLR, and—interestingly—a 3.5mm 4-pole balanced jack. The two 3-pin XLR jacks double as 1/4" single-ended outputs, and there's also a standard unbalanced 3.5mm jack specifically for IEMs. No matter what your headphone might be, iFi has you covered, with the soon-to-be-released electrostatic transformer box being the last piece of the puzzle. Okay, I suppose it's still missing a few obscure options like the 2.5mm TRRS jack favored by Astell & Kern, or that Ray Samuels/ALO mini-balanced connector, or the so-called "hirose" jack used by iBasso over the years. None of these are serious omissions as far as I'm concerned.

Gain on the device can be set to 0dB, 9dB, or 18dB via front panel switch, meaning everything from sensitive IEMs to the HiFiMAN HE-6 can be dialed in quickly and accurately. iFi also gives users a choice between full solid-state or tube operation, as well as a "Tube+" option, the ramifications of which I'll discuss a bit later.

As if that wasn't enough, the Pro iCan sports some unique sound enhancement options. First is something called "3D Holographic" sound, which is iFi's proprietary take on crossfeed. It's noteworthy in that it has two independent circuits—one each for headphone out and line out, with each offering several different levels of enhancement. Next is "XBass" which iFi calls a "Correction System" rather than merely a bass boost. It provides a 12dB bump centered at your choice of 10, 20, or 40 Hz. Both 3D Holographic and XBass are handled entirely in the analog domain, and I appreciate the fact that both can be tweaked beyond a simple "off/on".

The Guts
Internally, the iCan Pro is a fully discrete balanced differential design, with a MOSFET-buffered bipolar output stage biased deeply into Class A. It's a direct-coupled design with a DC servo to eliminate any DC offset coming from your source. The input stage is where we get options—choose the J-FET based solid-state implementation, or the tube section which uses a NOS pair of General Electric 5670 triodes.

This differs from most audio devices with defeatable tube sections—in nearly all other cases, the underlying solid-state circuitry is always in play, and the tubes act as a buffer on top of that. iFi goes a different route, giving us two completely separate designs acting independently of one another, either one being activated with the flip of a switch. The "Tube+" option makes for a third option, using the tube input stage but dialing back negative feedback to provide superior transient response along with a small increase in low-order harmonics. This makes for three fairly unique sounds, each with distinct advantages in certain circumstances.

The power supply starts with a large external power brick labelled as "iPower Plus". This is no mere wall-wart but rather a powerful outboard supply delivering 15V/4A with very low noise. The compact dimensions of the Pro iCan mean internal real estate is lacking—the external brick is practically as long as the amplifier itself. Keeping it outside the chassis also allows for isolation (via good old fashioned distance) from stray EMI and RF emissions. The Pro iCan then takes the incoming signal and does extensive conversion and additional filtration, providing ideal power for each separate stage of the device—6V to heat the tubes, 60V for the input stage, and +/- 16V for the output stage.

iFi has been selling power enhancement and filtration products since their early days, so it's not surprising to see plenty of attention to detail here. There is, in fact, an existing product in the catalog called the iPower which has been very positively received, which makes me to wonder if the included power brick might eventually be sold as a stand-alone product. No insider info here though, just pure speculation.

Output impedance measures under 2 ohms for single-ended outputs, and double that for balanced jacks. That's low enough to avoid problems with the vast majority of headphones and IEMs on the market. Power levels are absurdly high—max output in balanced mode is 14W into 16 ohm loads, with voltage swings as high as 23V into 600 ohm loads. The single-ended outputs cut those numbers down by more than half, which is still extremely potent. I have not encountered a headphone the Pro iCan couldn't drive with utmost authority.

That's a lot of features, but none of it matters if the resulting sound isn't of the utmost quality. As you'll read on the next page, iFi got the formula just right.