iFi Audio iDSD Diablo 2 portable headphone amp/DAC review

As desktop hifi solutions go, iFi Audio’s iDSD Diablo 2 DAC/headphone amp is one of the most versatile battery-powered devices I’ve encountered. We already rate the audio specialist as a master of mini hifi for its Zen and Zen Air phono stages, and I’ve enjoyed experience with several of its outstanding digital home audio solutions in former editorial roles. But with music lovers increasingly getting their hifi kicks while on the move, iFi has come up with more ways than most to boost the portable audio experience with a series of devices aimed at anyone who takes headphone listening seriously.

Its ten-strong portable audio series starts with the iFi Go Link (£59), closely followed by the recently introduced Go Link Max (£79) – both aimed at high-quality audio fans on a budget. There’s a model for just about every kind of user at increasing price points, right up to the £1,299 iDSD Diablo 2 portable DAC/headphone amp flagship on test here.

The crimson king

Housed in a striking crimson-coloured chassis, the Diablo 2 is the high-octane next-gen version of the Diablo-X DAC/headphone amp (£899) that launched in 2021. Billed as the devilish flagship successor, the Diablo 2 portable is fiendishly flexible and the company’s most powerful battery-powered design so far, but it costs £400 more.

In terms of market rivals, the iDSD Diablo 2 is over 3x more expensive than the universally praised Chord Mojo 2 (£395) – my go-to portable DAC for listening to music on the move. On the other hand, it offers wider support (depending on your audio priorities) and is more affordable than the Chord Hugo 2 (£1,799) that takes care of DAC duties in my main hifi setup at home.

Although it’s not without competition from several good looking rivals (not least among its iFi Audio siblings), the metallic crimson chassis is one the hottest-looking portable designs I’ve seen so far. The multiple grooves that decorate the casework (described as ‘rails’ by iFi) aren’t purely for cosmetic reasons, but also help the chassis dissipate heat more effectively – no doubt, preventing the powerful built-in amplifier from overheating while driving demanding headphone designs.

Output power and sensitivity handling are said to be improved over its predecessor to cater for a wider range of headphone designs, including delicate in-ear monitors (IEMs) through to demanding over ears. The balanced dual-mono circuitry claims a maximum power output of 2,450mW at 32 ohms to the single-ended 6.35mm output, and 5,180mW at 32 ohms to the 4.4mm balanced output, making it considerably more powerful than a MacBook Pro’s headphone stage and iFi Audio’s most powerful portable headphone amp design so far.

There’s a power mode selector on the front panel to adjust the sensitivity level to best suit your connected headphones: Normal for IEMs, Turbo for mid-sensitivity headphones, and Nitro for more demanding headphones. And as with its predecessor, the Diablo 2 is engineered to handle xMEMS solid-state piezoelectric, micro-speaker technology via a dedicated mode switch on the front panel, said to maximise performance with these emerging headphone designs.

The volume control on the front panel feels nicely weighted, and used in conjunction with the iEMatch switch on the underside provides a useful range even with high-sensitivity headphones and IEMs. There’s an effective (but fiddly to access) lock to secure the volume level’s position, which is a reassuring protection from sudden increases when listening on the move. Lastly, the multifunctional LED shows power on, input source, and Bluetooth pairing mode.

Demon days

While the Diablo 2 retains similar dimensions to its predecessor, the chassis weighs more at 455g (compared to 330g for the Diablo-X). Despite the extra weight, though, the unit was entirely practical for portable audio duties during my tests.

In tabletop mode, several of the chassis grooves can be fitted with the supplied ‘wing’ supports to elevate the controls and headphone jacks. The supports slide into position to raise the front panel to an angle for easier access when connecting up headphones and adjusting front panel controls.

Two pairs of customising wings are supplied offering different gradients, along with various cables and adaptors to connect the DAC/headphone amp to almost any kind of wired playback source. Sadly, though, there’s no cable to connect the 4.4mm balanced line-level output to hear how the Diablo 2 performs as a DAC when connected to my Musical Fidelity M6 500i hifi amplifier as part of my regular listening setup. If you want this, you’ll need to purchase the 4.4mm-to-XLR SE cable sold by iFi Audio for £50.

Lastly, a soft carry case is supplied for transportation of the device and its cables, as well as an iPower 2 mains adapter to charge the built-in 4800mAH Lithium-Polymer battery pack.

The company has a reputation for being forward thinking when it comes to supporting the latest tech and formats, and the Diablo 2 upgrades on its predecessor’s USB-A port with a move to USB-C (a USB-A-to-USB-C adapter is provided). Additionally, it introduces a 4.4mm balanced line input/output at the back along with wireless Bluetooth 5.4 connectivity with support for aptX Lossless, aptX Adaptive, LDAC and LHDC codecs. There’s also a 3.5mm S/PDIF that handles optical inputs via the supplied adapter.

Performance

Format handling boasts PCM up to 32-bit/768kHz with support for MQA decoding, and DSD up to 22.6MHz (DSD 512) using customised dual Burr-Brown DAC chips powered by a 32-bit, 16-core XMOS Cortex microcontroller.

With the Diablo 2 connected to my MacBook Pro M3 2024 via the Hi-Res Audio USB-C port, I started my listening with a pair of Sennheiser HD 600 open-back headphones plugged into the 6.35mm jack. I’ve been listening to these £399 cans since I walked away with a set following a visit to its Tullamore-based factory in Ireland at the beginning of 2024. The audio specialist makes several of its reference-grade headphones there, including the Sennheiser HE 1 £60k statement headphone system, and I was lucky enough to get some hands-on experience and build my very own pair of HD 600 headphones, which have become my go-to open-ear headphones for hifi listening.

For this listening test, I streamed my go-to Tidal playlist via the Audirvana desktop music player integrated with my Tidal and Qobuz streaming subscriptions and my network-attached Melco music library.

The Diablo 2 drives the Sennheiser HD 600s with impressive conviction and presents Alone (24-bit/96kHz FLAC via Qobuz) – the lead single from The Cure’s 2024 album Songs of the Lost World – in a skillful way. The head-fi combo feels nicely matched. There’s plenty of insight across the frequency range to handle the distorted guitars and edgy synths in an effortless manner, and the track’s disjointed sound makes more sense with this partnership.

Hans Zimmer’s Now We Are Free from the first Gladiator movie soundtrack also featured on the 2024 Gladiator II soundtrack. It’s intriguing to listen to Lisa Gerrard’s vocal in the original 16-bit/44.1kHz FLAC file release and compare it to the hi-res 24-bit/48kHz version on the Gladiator II soundtrack. Both versions were streamed via Qobuz, but the iDSD Diablo 2 did a spectacular job of showcasing the step-up in resolution. When tracks are played one after the other, the newer release had more detail and spatial depth to the soundstage that’s clear to hear.

Swapping to a pair of Campfire Audio’s Andromeda Emerald Sea IEMs connected to the 4.4mm balanced jack output also resulted in an open and transparent sound. In fact, the performance from these in-ears was better than I imagined. Streaming Gustav Holst’s The Planets conducted by Simon Rattle with the Berliner Philharmoniker (24-bit/44.1kHz FLAC via Qobuz), showcased the recording’s rich sound with all the power and foreboding I’ve come to expect from the suite’s opener Mars, the Bringer of War.

I confess, the step-up in performance with these IEMs connected to the Diablo 2 was something of a relief. As despite the Campfire Audio’s £1,300 luxury price tag, I’ve often found their mid-frequency performance to be on the brash and blurry side. But connected to the Diablo 2’s balanced headphone circuitry, they sounded more together and delivered the best performance I’ve heard from them so far.

Although I’m currently without a playback device that supports aptX Lossless or LHDC streaming over Bluetooth, my Sony Xperia 1 IV mobile connected to the Diablo 2 via LDAC, achieves a wireless audio connection over Bluetooth up to 990kbps.

Swapping to a pair of Grado SR80x open-back headphones (a great budget option for £130), LDAC streams gave a strong, engaging performance with Deadmau5’s Let Go (24-bit/44.1kHz FLAC via Tidal). Any Bluetooth codec compromises appear marginal, and my only criticism is of a slightly restrained sense of energy with marginally less refined high frequency details.

In Summary

The iDSD Diablo 2 is a well thought out device that works as a desktop solution as well as one you can use on the move. If you do stray away from the desk, though, you’ll need to keep an eye on the battery levels… The iFi doesn’t make any battery life claims – most likely because its playback time is so dependent on external factors such as the connection and headphone type in use – and the battery did run out of juice after a few hours mid-review.

That aside, the iFi Audio iDSD Diablo 2 gives an undeniable audio boost that surpasses any laptop’s built-in headphone stage. It’s one of the most powerful portable amplifiers I’ve tried, and flexible enough to accommodate a wide range of wired headphones. Its capabilities with upmarket IEMs are clear to hear, and it’s here where it justifies the price tag.