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iFi iDSD Diablo 2 DAC/headphone amp

Three years ago, UK-based iFi launched the iDSD Diablo headphone amp, garnering enthusiastic reviews by the fistful. Take this, for example: “the iFi iDSD Diablo - to me, sonically - is the best iFi DAC amplifier”. 

Recently, the second version (the iDSD Diablo 2) has been released and, while bearing little in common with the original (except that it’s red), it is every bit as impressive - more so, in fact. It’s a truly substantial design in every respect, absolutely bursting with practical features to propel your headphone listening to perhaps previously unheard, and certainly guaranteed, levels of enjoyment and involvement.

What iFi doesn’t know about DACs and headphone amplification isn’t worth worrying about. The iDSD Diablo 2 is designed for headphone aficionados, and with that in mind it ticks an awful lot of very refined boxes. It’s the result of a thorough rethink, both inside and out, of the original Diablo and results in greater sophistication in both performance and operation. While the original Diablo relied on cable connection to the source (laptop, phone, tablet), the iDSD Diablo 2 ups the ante by featuring the latest generation of iFi’s proprietary Bluetooth engine, complete with aptX Lossless support – iFi claim this as a world first for portable DAC/headphone amps.

Also on board is the latest Bluetooth version, 5.4 - it was announced last year and ensures the greatest wireless range and stability between source device and DAC. The Diablo 2 can store up to eight paired Bluetooth source devices in its memory, making it simple to switch sources.

It is difficult to find an avenue that iFi hasn’t thought about exploring in terms of source and playback. So the Diablo 2 has a generous number of sockets, switches and indicators - and they all have useful functions,  rather than representing a touch of glittering frippery.

Rear panel first. There are two USB-C sockets (for output and charging), with a discrete battery status LED that changes colour depending on the level of charge in the high-capacity 4800mAh lithium-ion battery. And there’s also a small, flush multi-function button for Bluetooth pairing and input selection. This links to an LED indicator on the front panel, so there’s no need to scrabble around checking what’s going on at the rear.

Tucked away on the underside is a small ‘IE Match’ switch, which in effect optimises power output for high-sensitivity headphones and in-ear monitors (IEMs). It works - listening on balanced IEMs, the switch gives a much finer degree of volume adjustment and delicacy of sound when activated.

Thankfully, the fully featured front panel is logically and neatly laid out. The dominant feature is a large, lockable, knurled aluminium volume pot with smooth operation and delicate degrees of output – there’s none of that ‘slightest nudge and your ears verge on exploding with excessive volume’ problem here. This is subtle engineering at its best.

Two sockets are provided for output: a standard 6.3mm (an adaptor for headphones with a 3.5mm jack plug is provided), and a 4.4mm balanced socket.

A small slide-selector adjusts power output: ‘Normal’ (0dB), ‘Turbo’ (+8dB), ‘Nitro’ (+16dB). Your selection will depend on your headphones’ or IEMs’ sensitivity.

There is also a degree of future-proofing. Depending on what you read or who you believe, the yet-to-be-widely available xMEMS new solid-state speaker technology could be a significant disrupter of the headphone and IEM market in the next few years. It combines semiconductor technology with moving parts, and has the potential to produce remarkable high-frequency fidelity. If it’s a goer, the Diablo 2 is in pole position to take advantage - and if that doesn’t come to pass, well, there’s only a small switch on the front facia that won’t get much use.

The final front panel feature is a tiny LED that delivers a multitude of colours to indicate what audio format you are playing, both for Bluetooth and wired connections. You certainly shouldn’t feel short-changed - there’s a choice of seven formats on each including aptX or aptX Adaptive for Bluetooth and hi-res 44.1 or 88.2kHz, DSD and (perhaps surprisingly), MQA and MQA Masters. There’s ample opportunity for nerdily switching sources of a recording and playing ‘spot the difference’. For normal people, though, it’s enough to know that it is extremely simple to set up and use. Hats off to iFi for including a really simple guide to getting the iDSD Diablo2 up and running within minutes, too.

Sound quality

Sometimes I get to test kit that sounds great but that takes a degree of fiddling to get the best out of it. The converse can also be true: sometimes performance comes secondary to convenience. What makes the Diablo 2 such a delight is its ability to sound wonderful right from the get-go, while not requiring the user to have a degree in applied mathematics to get the best from it. And it sounds even better with a few hours of playing under its belt.

The wireless connectivity delivering aptX Lossless works effortlessly, with simple, fast wi-fi connection. Used with a variety of computers, phones and tablets, the sound with both IEMs and high-quality over-ear headphones is so much more fulfilling than listening to the source directly - it’s an altogether richer, warmer, fuller, more detailed sound, with no drop-outs or glitches. That all-too-familiar sensation of listening to a portable source directly and it sounding like you have your head in a sack of rolled oats is, mercifully, far from apparent.

But even the excellent wireless connection is surpassed by the wired option. Connected by a standard USB-C cable directly to a MacBook Pro, or Samsung tablet or phone, for example, just seems to add another level of involvement to your listening.

Given the dimensions of the Diablo 2, I struggle to find a scenario where using it wirelessly is better than plugging it into the source. It weighs in at close to half a kilo - you are hardly likely to go out for a run with it in your pocket, or on a train or plane. ‘Portable’ is all relative - and a wired connection offers no obvious downside and superb results.

Besides its definition, clarity and depth, the soundstaging provided on some recordings is exceptional - some of the best I’ve ever heard. You feel as if you are sitting with the engineer in a studio guiding the sound through the channels - but at no time does music sound clinical, clunky or, erm, digital.

iFi’s blurb says that it takes a ‘music first’ approach in its design. That philosophy is writ large in the iDSD Diablo 2’s performance.

The MQA option is worthy of note. When switching to streaming from TIDAL, an ‘additional settings’ box pops up - this allows for MQA (or MQA Masters) passthrough, so that it’s the Diablo 2 doing the decoding rather than the source player. Finding an MQA-treated track on TIDAL that you know and enjoy gives results that can be spellbinding when compared to what you might have previously heard. Rediscovering the 2014 album Buena Vista Social Club Presents, with all its quirky originality, was as exciting a listen as the first time I heard it.

Living with

There’s no two ways about it: the Diablo 2 is a striking, classy design. The thoroughly modern fins that are an integral part of the solid aluminium body both aid heat dispersal and act as fixing points for its small legs. They offer a variety of methods for positioning the Diablo 2, while also giving it the semblance of something from Transformers or Thunderbirds (if you are of an age to remember them)…

On the inside, the Diablo 2 is clearly a complex piece of engineering - so iFi has pulled off a winning external design. What initially looks a little daunting, thanks to its plethora of sockets, switches and knobs, all falls nicely into place once you begin to use it.

While looking entirely at home on a desktop plugged into a laptop, it is easy to forget that this is (according to iFi) a transportable unit - so it functions as happily on the move as it does at home. The claims for battery life (iFi suggests between six and 12 hours playing time, depending on volume and how hungry your headphones are) seem accurate. And it’s possible to listen while charging, too - and the Diablo 2’s charging circuitry contains noise-cancellation smarts, ensuring that sonic performance is untroubled when the unit is driven by mains power.

In effect, there isn’t a noticeable difference in listening when the unit is running from battery power, charging from a laptop, or the mains. Which all adds to the Diablo’s considerable versatility and charm.


The Diablo 2 can genuinely improve the listening pleasure for anyone who connects wired headphones directly to a source such as a laptop, computer, phone or tablet. With the iDSD Diablo 2, iFi has delivered not just a fabulous pleasure ground of sonic abilities, but also something that’s simple to use. And while some of my reviewing colleagues have often been a tad quizzical over the operational ease of some iFi models, there is not a hint of quirkiness with the iDSD Diablo 2  – it’s straightforward and unambiguous in every respect. If I was being Grinch-like and looking for a quibble, then, yes, it would be great if it were smaller and lighter, and thus more portable. But if that traded off against sonic abilities, then I say take the Diablo 2 for what it is. In the world of headphone amplification, I’ll happily say that this is one of this year’s great finds.

Listening notes

Esther Abrami & the City of Prague Philharmonic Orchestra Cinéma

On Tiktok, Esther Abrami is doing for the violin what Anna Lapwood has done for the organ - 500,000 followers and growing.This is lush, superbly recorded, laid-back and unchallenging as it passes through movie and TV themes. There’s so much information warmly (in a good sense) captured and perfectly ordered, without ever being clinical. Abrami is French, so of course the album includes tracks from some French cinema classics: Amélie, The Little Prince and the excellent The Chorus.

Alison Krauss New Favourite (DSD)

Hard to believe this recording is over 20 years old, and predates her successful duets with Robert Plant. This DSD recording sounds as fresh and as lively as if it were done yesterday - and while bluegrass isn’t everyone’s jug of moonshine, Krauss’ voice is especially evocative, supported by a tight-knit band of steel guitar, banjo and slap bass. The dynamic range is enormous here. 

Anga Diaz Conga Carnival (TIDAL, MQA)

A chaotic soundscape from the 2014 MQA-charged Buena Vista Social Club Presents album, as lively and atmospheric as being there, with more horns than a troop of rhinos, wonderful harmonies and infectious bass line. Summer is here!

What the press say

Why you should buy it

You have to love your headphones, as many of us do, to splash out £1300 or so on this remarkable device. But if you decide to go for it, make no mistake: you are going to be richly rewarded for years to come. The quality from such a diminutive device is truly captivating, especially with all but the ropiest of recordings.

Versatile in its abilities and easy in its approach, the Diablo 2 complements the very best of IEMs and headphones. Just a bit too large for your average pocket, though…

Video review

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