iFi audio iDSD Diablo

General Information

iFi ushers in the New Year with the best battery-powered DAC/headphone amp the company has ever produced – the devilishly brilliant iDSD Diablo. Engineered to sit proudly at the top of iFi’s illustrious range of mobile and transportable devices, the Diablo is built for the purists – the true headphone enthusiasts who crave pure, unadulterated sonic performance.

With dimensions of 166x72x25mm, its size is similar to DAC/amps in iFi’s long-running, transportable micro iDSD series, with a built-in, quick-charge-compatible battery that makes it easy to move from desk to living room to travel bag. Its sleek new design and fiery red finish, however, mark it out as distinctly different.

Like a high-performance sports car designed for uncompromising speed, the iDSD Diablo sets aside facilities offered by other iFi DAC/headphone amps – sonic tailoring options and Bluetooth connectivity, for example – to focus on pure sonic power, featuring ultra-high-quality circuit components and the ability to drive any headphones on the planet with aplomb. Simply connect your digital source via USB or S/PDIF, plug in your headphones and prepare for a riveting musical ride from this elite-class digital audio engine, expertly tuned to achieve captivating speed, scale and dynamic range.

DAC’s entertainment

The iDSD Diablo’s digital stage incorporates a Burr-Brown DAC chip that iFi uses extensively, selected for its natural-sounding ‘musicality’ and True Native architecture. Here, two of these chips are installed in a custom ‘interleaved’ configuration – this enables four pairs of differential signals (two pairs per channel) which lowers the noise floor, improves channel separation and enhances the DAC’s ability to resolve fine musical detail and micro-dynamics.

iFi’s experience with this Burr-Brown chipset means it knows how to make the most of it, but the creation of an exemplary digital stage involves more than the selection of a particular DAC chip. One such critical component is the XMOS chip that processes the audio data received via the USB and S/PDIF digital inputs. The iDSD Diablo uses a new low-latency XMOS microcontroller with greatly enhanced processing power – compared to the current generation of eight-core chips, this new 16-core IC delivers double the clock speed (2000MIPS) and four times the memory.

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iFi’s in-house digital development team has programmed the XMOS firmware to optimise sound quality and ensure a perfect partnership with the DAC circuitry. Extensive jitter-eradication technologies are also applied to the digital stage, including an enhanced version of iFi’s GMT (Global Master Timing) femto-precision clock featuring a new crystal oscillator.

Every music format at the highest quality

Hi-res audio support is state-of-the-art, handling PCM data to 32-bit/768kHz, all levels of DSD up to DSD512, and single- and double-speed DXD.

Thanks to the Burr-Brown DAC chip’s four-channel True Native design, PCM and DSD take separate pathways – this enables DSD, as well as PCM, to remain ‘bit-perfect’ in its native form right through to analogue conversion. This is often not the case with DAC devices from other brands – even if DSD compatibility is stated, many such DACs convert DSD signals to PCM.

MQA – the hi-res streaming codec, as used by Tidal’s ‘Masters’ tier – is also supported through the USB and S/PDIF inputs, with full decoding of MQA files up to 384kHz thanks to the processing power of the new 16-core XMOS chip. This means that the full ‘three unfold’ decoding process is performed internally, as opposed to only the final unfold in the manner of an MQA ‘renderer’. Globally, MQA has become an important consideration for any comprehensively equipped DAC; for Tidal Masters subscribers, the iDSD Diablo is a great way to make the most of the superior sound of which this streaming service is capable.

PureWave – balanced circuit design for the purest sound

The digital stage is only half the story in any DAC/headphone amp; when it comes to the crucial analogue circuitry, many such devices fall short. Balanced, differential analogue circuit design has long been championed for its ability to reduce noise and cross-talk within the signal path by fully separating the left and right channels. However, this is more complex and costly than single-ended circuitry, and so has traditionally remained the preserve of high-end hi-fi components.

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iFi has gradually introduced fully balanced circuit design across its range – first in the flagship Pro Series components, then in the entry-level ZEN Series devices. The company’s two newest DACs, the mains-powered NEO iDSD and transportable iDSD Diablo, benefit from further refinement of their balanced, symmetrical dual-mono topologies with short, direct signal paths. iFi calls this circuit concept ‘PureWave’, referring to the sonic purity it achieves thanks to exceptional linearity and infinitesimally low levels of noise and distortion.

Powerful amplification delivers musical gratification

Already renowned for the performance of the amp stages in its DAC/headphone amps, iFi has ensured the iDSD Diablo is its best-ever transportable amplifier, designed to deliver reference-level sound. Able to drive all manner of headphones with ease, from highly sensitive in-ear monitors to current-hungry planar headphones, it delivers prodigious power (up to 5000mW), propulsive energy and engaging dynamics, coupled to a remarkable ability to resolve fine texture and detail.

The great variation in the electrical characteristics of different headphone/earphone types is accommodated by the provision of three settings enabling the user to adjust power and gain to suit whatever the amp stage is tasked with driving: ‘Turbo’ ramps up the level of drive for current-hungry headphones, ‘Eco’ dials down the power to suit high-sensitivity in-ear monitors and/or extend battery life, and ‘Normal’ sits between the two.


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High-quality components are used throughout the iDSD Diablo’s circuitry, utilising its larger form factor in comparison to smaller, pocket-sized DAC/amps. Custom ultra-low-distortion MOSFET op-amps feature in both the digital and analogue stages, together with a hand-selected range of capacitors including the multilayer ceramic type TDK C0G and aluminium-polymer type Panasonic OS-CON. MELF thin-film resistors and inductors from Taiyo Yuden and Murata also feature in the circuit design.

These are all more costly than commonly used circuit components, but class-leading qualities such as low ESR (Equivalent Series Resistance), high stability and low distortion pay great dividends in terms of sound quality. Many hours of listening tests, alongside rigorous analysis in the lab, has determined the optimum circuit design to deliver maximum musical enjoyment.

An important aspect of the iDSD Diablo’s circuit design is its direct-coupled nature (no coupling capacitor is present), achieved without a conventionally applied DC servo; iFi calls this design Servoless Direct Drive. Also important is the use of a high-quality analogue potentiometer to control volume – its sonic transparency compared to chip-based volume controls makes the most of the clarity and resolution of the amp stage.

OptimaLoop – negative feedback that is purely positive

‘Negative feedback’ is used in amplifier circuits to compare the output signal with the input signal and correct errors, in order to control gain and reduce distortion. For sound quality, this is positive; but commonly applied, one-size-fits-all ‘global negative feedback’ can highlight different problems whilst solving others – corruption of the error signal, phase shifts, group delay and so on can all have a negative impact on sound quality.

Recognising that different parts of a circuit benefit from specifically optimised feedback loops, iFi has developed a negative feedback system that is much more accurate than the usual approach. This incorporates multiple feedback paths instead of one global loop, each path optimised for a particular function and working synergistically with the others to deliver optimal overall performance. iFi calls this new configuration OptimaLoop.

This power does not corrupt

In keeping with the iDSD Diablo’s focus on pure, unadulterated performance, much attention has been applied to the power supply circuity. Battery power provides a theoretical performance advantage over mains power, with ultra-clean and stable DC current avoiding the issues that can be introduced by mains electricity with its dips, spikes and noise-inducing RFI/EMI pollution. There are also potential sonic downsides to battery power, however, resulting from low output voltage and inconsistent output impedance as batteries discharge – these issues are fully tackled by the iDSD Diablo’s design.

In order to make less efficient headphone types sing – planar magnetic designs, for example – the voltage needs to be stepped up from 3.7V to +/- 15V. This is achieved through the use of a step-up converter running at 1.2MHz – a frequency far beyond audibility that is easier to filter than a typical switch-mode supply, enabling high linearity and ultra-low noise.

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High-bandwidth power supply circuity is dedicated to each critical part of the iDSD Diablo’s design, with independent linear regulation delivering excellent PSRR (Power Supply Rejection Ratio) performance. The headphone amp stage eschews IC regulators in favour of Panasonic OS-CON capacitors, delivering 2320uF between them. The DAC section benefits from an ultra-low-noise regulator with additional passive filtering, reducing high order harmonic distortion and, in turn, jitter. Even the USB input stage benefits from dedicated regulation and multistage filtering, and the microprocessor control circuitry (often a local source of digital noise) has separate regulation, too.

Get connected

At the front of the unit, alongside a standard 6.3mm single-ended headphone socket, resides a 4.4mm Pentaconn output for headphones offering balanced connection. An increasing number of high-quality headphones and in-ear monitors either come so equipped or give the option of detaching the cable and upgrading to a 4.4mm Pentaconn connector (this output is particularly recommended for tougher headphone loads). In terms of power, the balanced headphone output delivers 12.6V/4980mW into 32 ohms and 19.2V/611mW into 600 ohms, while the single-ended output supplies 8.8V/2417mW into 32 ohms and 9.6V/153mW into 600 ohms.

At the back of the chassis are two digital audio inputs: USB-A and an S/PDIF socket that accepts both electrical and optical signals, the former via a 3.5mm connector and the latter via a supplied adapter. Unusually, the USB-A input features a ‘male’ connector, rather than a typical ‘female’ port – this arrangement provides greater mechanical integrity than the USB/Micro USB ports commonly used by other DAC/headphone amps. It also offers an advantage to users of iPhones and iPads with Lightning ports, because it accepts Apple’s Lightning to USB Camera Adapter directly without requiring an additional female-to-male USB adaptor. A separate USB-C charging port is also provided, along with a fixed line-level 4.4mm Pentaconn balanced output to connect an external amp.

A package worthy of reference status

In keeping with a reference-level product, iFi has been generous with the accessories supplied with the iDSD Diablo. The DAC/amp may be powered from the mains, as well as by its built-in battery; in order to ensure optimal sound quality when hooked up to the mains, iFi includes its iPower 5V AC/DC adapter, which engenders significantly less noise than other similar devices thanks to Active Noise Cancellation and sells separately for £49.

Also included is a 4.4mm Pentaconn to XLR balanced interconnect cable, enabling the iDSD Diablo to be connected to an amp and speakers (or a pair of active speakers) with balanced XLR inputs. Other supplied connectors include a short (15cm) USB-C to USB-A audio cable, as well as an extension cable – all USB3.0 compliant – plus a USB-C charging cable and an adapter to connect headphones with a 3.5mm jack to the 6.3mm single-ended output. Even a travel case is included.

In addition, the first iDSD Diablo production run includes iFi’s iPurifier3 in the bundle – retailing separately at £129, this USB ‘noise-buster’ is designed to tackle all aspects that degrade sound quality over USB thanks to a precision mix of tech including Active Noise Cancellation. It all adds up to a package of accessories worth around £300.

Delivering devilishly good sound for headphone lovers, iFi’s iDSD Diablo is available from selected retailers from Friday 15th January at an RRP of £899, (€999, $899).

Latest reviews

Slater91

100+ Head-Fier
Diabolically good
Pros: Sturdy built with supercar-like design

Possibly the most powerful portable device: 5 W output at 32 Ω!

Balanced output through 4.4 mm jack

Incredible amount of accessories
Cons: Requires separate USB-C cable for charging

Loses all the extra features of predecessors

Charge indicator is impractical

Should have included an IEMatch feature
iFi iDSD Diablo review.JPG


When I was a child, back in the glorious Nineties, I remember I had a model car of what was among the fastest cars back then: the Lamborghini Diablo. It was fantastic and its design and colour really gave the impression of speed and power. Being around 3 years old, I obviously destroyed it and I still regret that. Now, I don't know if the Italian supercar is the inspiration behind the iFi iDSD Diablo, but surely the impression of unrestrained power it gives is the same as the car - and for all the good reasons.

This review was originally posted on Soundphile Review.

Disclaimer: thank you to iFi for sending out this unit on loan. The iDSD Diablo is a hell of a lot expensive (yes, I'm going to make jokes for the whole review), retailing at £999. Additional info on the official website.

Accessories & Packaging​

iFi iDSD Diablo review 2.JPG


The iFi iDSD Diablo comes in a very different package from that of the other micro iDSD devices: it's much larger and more akin to the Neo iDSD. That's because the amount of accessories has increased exponentially and includes:

  • an iTraveller carrying case
  • an iPurifier3 (which is, unfortunately, limited to just the first batch)
  • a 3.5 mm to 6.3 mm jack adapter
  • a USB-A male to USB-A female cable
  • a USB-B male to USB-B female cable (useful if you want to use the iPurifier)
  • a short USB-A male to USB-C male (to charge the
  • a short USB-C male to USB-A male (basically an OTG cable)
  • an optical to mini-optical adapter
  • an RCA to RCA cable
  • a 4.4 mm to double XLR cable
  • an iPower power adapter
  • a barrel connector to USB-C connector (to use the iPower)
The list is quite long and shows the sheer quantity of stuff iFi has put into this box. It's quite a complete set and I can't think of anything I would add to it.

Design & Build​

iFi iDSD Diablo review 3.JPG


Again, I don't know where iFi drew inspiration from, but the Diablo reminds me of a track by Rodrigo y Gabriela, Diablo Rojo. I know, that's quite an original association, isn't it? I totally don't know where I got that from.

It might be this, it might be Italian cars, it might be something else entirely - but as any fan of Warhammer 40000 knows, just the fact that the iDSD Diablo is red makes it faster, which is obviously great. On a less humorous note, the Diablo is obviously very noticeable in that it uses a very eye-catching colour for its chassis, with a black volume knob on the front. It's certainly unique in an industry dominated by serious, often sombre colours. At first I thought that, contrary to the other micro iDSD devices which use metal for their chassis, the Diablo used plastic. That's actually not the case: the iDSD Diablo's chassis is in fact made of metal just like all of its ancestors. The paint finish, though, is remarkably similar in feel to plastic (and a few hot days here in Scotland meant that it was hot enough for the metal not to feel too cold, tricking me into thinking it was plastic).

iFi iDSD Diablo review 4.JPG


The front hosts the aforementioned volume knob, a status LED which indicates the currently-played format (e.g. CD quality, MQA, hi-res, etc), a "turbo mode" switch (a gain switch, basically), a 4.4 mm port and a 6.3 mm port. The back, on the other side (sorry, I had to do this), hosts a full-size male USB-A connector, a female USB-C connector, a 4.4 mm port and a 3.5 mm port for optical SPDIF input. It's a rather complete set of features, but sadly there is no unbalanced line out, which can be a problem if you plan to use the Diablo as a DAC for an unbalanced amplifier.

iFi iDSD Diablo review 5.JPG


As with practically every single device by iFi I've ever tried, the iDSD Diablo, too, is built quite well and leaves no room for criticism regarding this area. If anything, some things have improved: the bottom of the device has in fact four rubber feet embedded in it.

The volume knob has a very good weight to it, so it is relatively hard to turn. While this might seem like a flaw, it is in fact a feature as it allows for very precise adjustments. It has a dead zone which goes from its starting position around 7 to around 10 - so in that area you can expect to have large volume imbalances between channels. This, together with other things, contributes to making the iDSD Diablo difficult to use with low-impedance, sensitive headphones and earphones.

Features & Specs​

iFi iDSD Diablo review 6.JPG


The Diablo is not a replacement for the other devices in the micro iDSD line-up: in fact it offers quite fewer options in terms of output power, filters and so on, only allowing you to select gain (you can choose between Eco, Normal and Turbo). This is in stark contrast to the micro iDSD Black Label, which offered almost any option under the Sun. It's as if iFi decided to take its previous offerings and extract their essence: lots of power and little compromise in terms of how the audio signal is treated. That's a philosophical approach that leads to some compromises, though, so this needs to be thought of carefully.

Unfortunately the volume of the line output is fixed and can't be controlled using the knob.

iFi micro iDSD Diablo

InputUSB (up to 32 bit / 768 kHz PCM/DXDx2, up to DSD512, MQA)
Bluetooth (up to 24 bit / 96 kHz)
Suitable headphones impedance32 - 600 Ω (at least)
Output impedanceN/A
Maximum output powerSingle-ended:
  • 2,417 mW (32 Ω)
  • 153 mW (600 Ω)
Balanced:
  • 4,980 mW (32 Ω)
  • 611 mW (600 Ω)
Frequency response10 - 80,000 Hz
THD+N (@1 kHz)< 0.002% (balanced)
< 0.001% (single-ended)
SNR> 120 dB (balanced)
> 114 dB (single-ended)
CrosstalkN/A


As is tradition for iFi, the iDSD Diablo uses a Burr-Brown DAC. The company mentions "[t]he Burr-Brown True Native® chipset" in its material, so I'm taking a guess and say there is a single DAC chip in this device, leading to it not being a "true" balanced design.

iFi iDSD Diablo review 7.JPG


On the other hand, the amount of power the iDSD Diablo gives you is astonishing and well into the territory of large desktop amplifiers. At an output power that's just short of 5 W at 32 Ω (theoretically double the output of the micro iDSD Black Label!), this device can drive anything under the Sun save for some earspeakers (e.g. Raal Requisite SR1, AKG K10000, etc). Speaking of output power, the lack of the IEMatch switch is felt when you try to use the Diablo to drive IEMs: it's just too powerful for them, so it ends up being just too loud without using an actual IEMatch or adjusting the volume via software on the source device.

Now, there's also something to be said about the steps of the gain selector. The difference between them is quite large, so going from one to the next means that you get a very large jump in volume, more so than on other amplifiers. This, coupled with the lack of an integrated IEMatch feature, means that it might be hard to use the iDSD Diablo with lower-impedance headphones.

Battery Life​

The iFi iDSD Diablo offers a whole day of activity, which clocks in at around 10 hours using relatively easy to drive headphones and the "eco" mode. The figures will probably be lower when using more demanding headphones, but the result is still quite good.

A major annoyance, though, is the lack of any indication that the battery is running out of charge and the necessity to use a second cable to power the device. "Traditional" desktop use is not quite as convenient as with previous micro iDSD devices, as you have to connect the Diablo to a charger for desktop usage - with all the inconvenience that this entails, of course. I would consider this a desktop device that you can optionally use on a battery, a bit like the Head 'n' HiFi Objective2 amplifier.

One thing about the battery is that it is always used. Even if you plug in the device to the mains outlet, that current will be used to charge the battery which is then going to power your headphones. There is just no way to use the power adapter directly to power your headphones. While this can have a good effect on audio (battery power is, by definition, clean and devoid of noise), on the other hand this might be an issue down the road, as after a few years of use I imagine the battery is going to give up and to be in need of replacement.

This also means that the iPower provided with the device is actually useless: it should theoretically offer less noise and therefore improve the performance of a connected device, but in practice this supposed positive effect is cancelled by the fact that the power to drive your headphones comes from the battery anyway.

Sound​

I tested the iFi iDSD Diablo using my notebook computer, an HP EliteBook 745 G5, and FLAC files (most ripped from CDs).

Despite removing the IEMatch feature, the iDSD Diablo is absolutely dead silent, even when using it with sensitive earphones.

Just like its predecessors, the iDSD Diablo doesn't really have a sound signature of its own that I can discern. In fact it is completely neutral to my ears, as I can hear no differences when comparing it to other DACs and amplifiers. As it offers an insane amount of power, it can drive anything I throw at it without breaking a sweat and with very good speed, too. Maybe (let's put some stress on it: maybe) there is a tad more micro-detail here compared to other devices such as, say, the nano iDSD Black Label - possibly thanks to the pitch black background.

One thing that I miss here is the various options that were there in previous models, such as XBass and 3D+, but the choice of iFi of focusing on pure performance has the side effect of removing these options.

Final Thoughts​

While thinking about what mark I should award the iFi iDSD Diablo, I thought: "you lose some, you win some". And that's exactly what has happened with the Diablo: it got some improvements over its predecessors, but at the same time it gave up some features. It's rare to see a company so hell-bent into creating a portable amplifier so powerful it beats most desktop counterparts, but here we are. And with this also come some compromises.

The iDSD Diablo has a lot of things I really like, from the incredibly powerful output to the balanced port, from the vast amount of accessories to the optical input. It also misses a few things I would have liked to see, such as an IEMatch feature to better drive sensitive earphones. All in all, though, the Diablo is incredibly competent and a great option if you want to experience the sound of very-hard-to-drive headphones with a small DAC/amp instead of large desktop devices. It's just fiendishly good at that.
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iFi audio
iFi audio
Fantastic work, many thanks :beerchug:

Wretched Stare

Head-Fier
Style and power incarnate
Pros: Power to run anything with minimal effort, great looks and build quality, very low ground noise and great accessories.
Cons: No Bluetooth or module, nor IE match or XBass on this model.
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The Diablo is the top flagship of iFi's DAC/Amps line-up.
Priced just a few hundred above the iFi Micro iDSD this offers a much more reference class listening experience. The box includes a plethora of accessories including a Carrying case, iFi USB Purifier with the first 1000 units only, 4.4mm pentacon to 2x XLR cable, USB male to female cable, USB-C OTG cable, the Power supply with a USB-C adapter, USB adapter,3.5mm to 6.35mm adapter and a 3.5mm optical adapter. The Diablo itself is very well made of all metal construction with that very bright red supercar paint job.
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Inputs and outputs are generous as is the amount of power and quallity parts inside.
Specs are as followed:
HIGH RESOLUTION - Dual Core Burr Brown True Native chipset supports all hi-res audio formats up to PCM 32 bit / 768kHz, DSD512, and MQA (decoder)
POWERFUL AMPLIFIER - Up to 4,100 mW headphone amplifier with balanced topology and 4.4mm output. Easily switch between Turbo (4,100mW) /Normal (785 mW) /Eco (265 mW) modes
AMAZING SOUND - Ultra-Low noise, low distortion (0.00006%) OV2028 OpAmp, devil bass reproduction, and unbelievable resolution provide an unbeatable experience
PORTABLE - Rechargeable battery provides 6-12 hours of listening, or play while charging
CONNECTIONS - USB A, S/PDIF digital and optical audio inputs; 6.3mm and 4.4mm headphone outputs.

I would have liked a Bluetooth module or adapter but given this is a reference class Dac its understandable, that said a IE match mode or adapter included would have been cool too but honestly its just nit picking because the device is just a great DAC/ Amp and virtually a flawless design.


Performance:

The unit came with the original release firmware, there are two other but the device was run off the stock for testing purposes. Using the device with a large variety of headphones and IEMs I noticed that most of my collection just needed normal mode including the panars. I had to borrow DT1990 to really test out the volume but alas turbo still had plenty of headroom. The Dekoni Blue sound fantastic on this as well as the Philips X2HR it makes them sound much bigger than they normally do.

Both Balanced and regular sounded amazing with the balanced being a bit more dynamic in Bass presentation. Overall the sound was neutral to balanced sound with great clarity and if there is any noise I certainly didn't find it. Bass presents with good control, power and clarity. Mids are forward yet perfectly positioned, Treble is clear and detailed with good extension. Unbalanced the Diablo has a slight warmth but is mostly clear and balanced sounding, with the 4.4mm it gets a little more brighter but the overall performance is that of a reference class device not coloring the sound adding anything or subtracting. Soundstage is open but stays close to ones head, sounding natural to the ears with good imaging.


Conclusion: This is the pinnacle of portable audio but that doesn't mean it isn't at home on the desk too. This would serve just as well as a desktop Dac/Amp as it does for portable. If your collection is IEMs this would be totally overkill but it would look good doing it for sure. The Diablo is a very well made portable with plenty of accessories and power to make even the most discerning audiophiles smile.
Sebastien Chiu
Sebastien Chiu
Thanks for the great read, glad you love it!

Ichos

Reviewer at hxosplus
Devilishly good
Pros: - Absolutely reference tuning
- Natural and very engaging sound
- Super powerful
- Dead silent
- Good battery life
- Fully balanced line out
- Optical in
- Independent charging port
- Excellent build quality
- Still compact for such a powerful dac/amp
- iTraveller case is of high quality
- Good quality 4.4 to dual XLR Cable
- First batches include an iPurifier 3
Cons: - Balanced output not suitable for very sensitive earphones
- Eco gain setting is too aggressive
- An extra lower gain would be great
- Line out is fixed only
- No bluetooth
- USB cables of mediocre quality
- An iEMatch should have been included
The Diablo was kindly provided by iFi as a loaner unit for the purpose of this review.
This is my subjective and honest evaluation of it.

Introduction

The brand new Diablo that was released at the beginning of 2021 is the top flagship of iFi's range of portable/transportable DAC/amps.
This is a great way to welcome the new year and a very promising start.

It retails for €999 and it is €300 more expensive than the previous flagship Micro iDSD signature.
Let's find out why.

IMG_20210404_194411.jpg


Technical specifications

Full specifications are available here - https://ifi-audio.com/products/idsd-diablo/

The Diablo is built for purists – the true headphone enthusiasts who crave pure, unadulterated sonic performance so it sets aside sonic tailoring as well as Bluetooth connectivity to focus on pure sonic power.
The Diablo , plain and simple is designed to deliver reference level sound.
In our opinion a bluetooth connection wouldn't affect the sonic performance that much and should have been included.

micro-iDSD-DIABLO_PCB_06.jpg


Dac converter and USB receiver

iFi uses two Burr-Brown DAC chips and the new 16-core XMOS chip to process the data received via the USB and S/PDIF digital inputs.
This means the iDSD Diablo can handle up to PCM 768, DSD 512, 2xDXD.
Both PCM and DSD remain ‘bit-perfect’.
It also provides full MQA decoding that is also available over S/PDIF so you can take advantage of any MQA CDs in your collection.
This new low-latency XMOS microcontroller has greatly enhanced processing power.
Compared to the current generation of eight-core chips, this new 16-core IC delivers double the clock speed (2000MIPS) and four times the memory (512KB), as well as the latest SuperSpeed USB standard.
iFi’s in-house digital development team has programmed the XMOS firmware to optimise sound quality and ensure a perfect partnership with the Burr-Brown DAC.

Extensive jitter-eradication technologies are applied to the digital stage, including GMT (Global Master Timing) femto-precision clock and intelligent memory buffer.
This represents a total ‘out-of-the-box’ systematic digital solution that solves jitter once and for all.

Topology

Balanced, differential analogue circuit design reduces noise and cross-talk within the signal path by fully separating the left and right channels. The iDSD Diablo benefits from further refinements to the balanced, symmetrical dual-mono topologies with short, direct signal paths.
Negative feedback is used in amplifier circuits to compare the output signal with the input signal and correct errors.
But there are drawbacks and iFi turns the negatives into positives with OptimaLoop.

31b198051c5908d593122d04e40f27fcd9df9611_2_690x487.jpeg


Headphone amplifier

While with the iFi NEO iDSD that we have previously reviewed (https://www.head-fi.org/showcase/ifi-audio-neo-idsd.24765/review/25111/) the headphone amplifier was a utility feature here it is a whole different story as the Diablo amplifier is the true star of the show , a real powerhouse.

Able to drive all manner of headphones with ease, the iDSD Diablo delivers up to 5000mW of prodigious power, propulsive energy and engaging dynamics, coupled with a remarkable ability to resolve fine texture and detail.
With 3 settings, you can adjust power and gain to suit your daily driver.
Turbo – ramps up the level of drive for current-hungry headphones
Normal – for most over or on ear headphones and
Eco – dials down the power to suit high-sensitivity in-ear monitors.

Power supply

As we all know nothing is more important than clean power and iFi has implemented some serious technologies behind Diablo's power supply.

Battery power provides ultra-clean and stable DC current avoiding the issues of mains electricity – dips, spikes and noise-inducing RFI/EMI pollution.
But there are sonic downsides resulting from low output voltage and inconsistent output impedance as batteries discharge.
These issues are fully tackled by the iDSD Diablo’s design.
In order to make less efficient headphones, like planar magnetics, sing, the voltage needs to be stepped up from 3.7V to +/- 15V.
They use a step-up converter running at 1.2MHz – a frequency far beyond audibility that is easier to filter than a typical switch-mode supply, enabling high linearity and ultra-low noise.

High-bandwidth power supply circuit is dedicated to each critical part of the iDSD Diablo’s design, with independent linear regulation delivering excellent PSRR (Power Supply Rejection Ratio) performance.
The headphone amp stage eschews IC regulators in favour of Panasonic OS-CON capacitors, delivering 2320uF between them.
The DAC section benefits from an ultra-low-noise regulator with additional passive filtering, reducing high order harmonic distortion and, in turn, jitter.
Even the USB input stage benefits from dedicated regulation and multi-stage filtering, and the microprocessor control circuitry (often a local source of digital noise) has separate regulation, too.

All the components used are of top quality and from well established brands such as Panasonic , Texas Instruments , Vishay MELF and muRata.
As with many other iFi audio products they have incorporated a custom OV Series operational-amplifier.
This top-notch component contributes to the extremely low noise, low distortion (0.0001%) and wide bandwidth.

Connectivity

At the front of the unit, alongside a standard 6.3mm single-ended headphone socket, resides a 4.4mm Pentaconn output for headphones offering balanced connection.
At the back are two digital audio inputs: USB-A and a S/PDIF socket that accepts both electrical and optical signals, the former via a 3.5mm connector and the latter via a supplied adapter.
The USB-A input features as per usual practice of iFi , a ‘male’ connector, rather than a typical ‘female’ port for greater mechanical integrity.
A separate USB-C charging port is also provided, along with a 4.4mm (fixed only) line Pentaconn balanced output to connect to an external amp.

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Accessories

As the iDSD Diablo may be powered from the mains, as well as by its built-in battery they have included the super silent, noise-cancelling iPower 5V AC/DC adapter to ensure optimal sound quality.

But since there is no way to bypass the battery of the Diablo even when it is fully charged and connected to the mains we can't see any benefits here except for marketing reasons.
Anyway the extra 5V iPower supply can easily find a place somewhere else so it is a welcomed bonus.

Also included is a 4.4mm Pentaconn to twin XLR balanced interconnect cable to connect the iDSD Diablo to an amp and speakers (or a pair of active speakers) with balanced XLR inputs.

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There are also included a short (15cm) USB-C to USB-A audio cable, as well as an extension cable plus a USB-C charging cable and an adapter to connect headphones with a 3.5mm jack to the 6.3mm single-ended output.

About the USB C to A cable there seems to be confusion because some batches include only a male to male one and some others include an extra OTG female to male.
Our sample was without the latter.

The balanced interconnect is of top quality but the USB cables are mediocre and not worthy of the premium price of the Diablo.
The USB extension that was included with our sample at one end was loose and twisting inside the plug.

The high quality iTraveller carrying case comes as a standard and with the first batch of Diablo's there is an extra iPurifier 3 included as a bonus.
An extra IEmatch should be welcomed and very useful.

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Physical and build quality

The unit is very compact and measures 166 x 72 x 25 mm weighing 330gr , so while it is not pocket friendly it is very easily transportable.
Build quality is top notch with an all aluminum case , finished - what else - in a fiery devilish red color.
The potentiometer knob is an aluminum one and all the plugs are heavy duty.

Set up

Setting up the Diablo is an easy and straightforward procedure.
USB OTG function is natively supported and we can use the Diablo with Android devices without the need of a special application.
The Diablo will run from it's internal battery without drawing power from the host device.
For Windows PC we have to install the included drivers that offer ASIO support.
If we run out of battery we can hook it up to the extra charging port and keep listening.

We have tested the Diablo with various Android phones and tablets , a Windows PC and with Cambridge Audio CXC CD transport through the optical input without encountering any problems at all.

Our unit came with the original release firmware but in the meanwhile two other versions were released.
The 7.0c GTO Filter and the 7.0 Cookies & Cream two filters that iFi is using and for other products too.
A detailed guide about the filter differences is provided at the iFi support center.

We have performed the first listening tests with the original release filter and then we have installed the new ones.
Both sound great with differences being quite minimal and after a while we settled down to the 7.0c GTO because it fitted our individual tastes better.
After installing one of the new filters you cannot revert back to the original one but there is no reason to do so because they sound better.

We should note that while playing music of various resolutions up to 24/96 (we never use higher formats) the color of the LED that displays the sampling rate stays always in magenta color.

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About power and noise floor

In order to better evaluate the Diablo we have used our best headphones such as the Meze Empyrean , the Sennheiser HD660S and 650 and the HiFiMan Ananda all balanced.
We don't own very difficult planar magnetic or very low sensitivity dynamic drivers so we didn't make use of the full power output.

With the above mentioned headphones we never reached for the normal gain - except a couple of times - and the Ecco was more than enough (balanced out).
The usable range of the potentiometer was between 8 o'clock to 3 o'clock so volume control was good but not perfect although always away from the channel imbalance region.

A few iem's were used to find out about noise floor and usability due to the excessive power of the Diablo.
We don't own ultra high sensitive iem's so we have tested with the FiiO FD5 and the Dunnu EST 112.
With these iem's we couldn't detect any audible noise and from the balanced output at Eco mode we got very loud at 10-11 o'clock.
So the balanced output is definitely usable but not optimal and for more sensitive earphones we have to use the single ended output.
That's not a big deal if you ask us but purists may complain due to the loss of the balanced signal integrity.

We do believe that iFi should have included an extra lower gain setting or the existing three ones could be differently and more proportionally arranged.
The Eco setting while usable is too aggressive for sensitive headphones and the normal setting is practically useless for most "normal" headphones.
An IEmatch should definitely have been included as a standard accessory.

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Sound impressions

Most listening tests were performed with the 7.0c GTO filter which to our ears poses a more analogue like character but as we have previously noted the overall sound signature remains intact with both filters and the differences are quite minimal.
You can easily experiment and settle down with your own preference.

You don't have to listen a lot in order to determine that this is an absolute reference presentation with dead flat frequency response and the utmost fidelity to the source material.
Amplifier and DAC work together in perfect harmony and alignment to produce a sound of great precision that is ruthlessly revealing of all the good and the worse parts of the recording.
This is high fidelity at its best and rest assured that the Diablo is going to do full justice to every headphone used no matter the price or type.
It is a flagship dac/amp worthy of all the TOTL headphones of the market and it will proudly exploit all the technicalities and highlight the sonic differences between various headphones and showcase their full potential.

The presentation is muscular and full bodied with deep and very controlled bass that sits tight and can exhibit infinite amounts of layering and definition even with the most demanding material.
Driver control is perfect resulting in a fast but steady and well paced sound with an inherent sense of the rhythm and spot on timing.
Macro dynamics are explosive and can only be compared to desktop amplifiers so with the Diablo it is the first time that we were able to experience such a sense of realism from a battery powered device.

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The feeling of silence is spooky with a pitch black background to help resolve even with the finest micro details that are presented in a well integrated manner.
The Diablo will reach very deep into the recording venue but it will never sound analytical.
All the available details are used in a clever manner to build up the sense of realism rather than becoming a self exposing proclamation to draw attention.

Of course as is to be expected mid and higher frequencies are perfectly linear but are rendered with some kind of harmonic warmth.
The Diablo can sound more engaging and analogue than the NEO iDSD at least the way we hear it.
Voices and mid range instruments are intense and very lifelike with an extra natural timbre.
Timbre and intensity are thankfully retained up to the higher registers that are well extended and never sound lean or harsh but on the contrary they do feel very organic and smooth though still full of energy and light.

Space allocation is one of Diablo's greatest strengths and with a suitable headphone , like for example the Meze Empyrean , the experience is just stunning.
The Diablo can easily draw an out of the head soundstage that expands in a three dimensional way to portray an immersive and holographic scene.
Depth layering is excellent as is the positioning and the Diablo can adapt from one person to the full orchestra always sounding in great proportion and full of natural reverb.

A flawless and very transparent sonic performance that is always engaging and natural sounding with an analogue like character free of digital glare that is a pleasure to listen for hours on.

Last but not least potential buyers should not overlook the balanced line output that retains all the excellent characteristics of the sound and can easily act as a high performance DAC with 2 channel speaker systems , passive or active.
(and external headphone amplifiers of course but we strongly doubt if anyone is going to need something better and more powerful than the internal amplifier)

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At the end

We are not going to enter here an endless debate whether someone might need such a powerful transportable dac/amp that is stripped off wireless connection plus sound tweaking features and is not very friendly with sensitive headphones.
That's up to you to decide and the only thing we can do is to assure everyone reading this review that the Diablo is easily one of the most powerful and reference sounding transportable dac/amps out there.
If you have decided that you need a minimal but super powerful dac/amp that will deliver the ultimate sound performance then the Diablo it is.
And don't say you haven't been warned that a few minutes of listening time with the Diablo aren't enough to feel the Devil's breath.

Test playlist - http://open.qobuz.com/playlist/5669033

Copyright - Laskis Petros 2021
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Soundizer
Soundizer
“The presentation is muscular and full bodied with deep and very controlled bass that sits tight and can exhibit infinite amounts of layering and definition even with the most demanding material.”

thank you for excellent review. In your opinion how does base quantity compare to iDSD Signature or Black Label when the XBASE on them is switched on?
Ichos
Ichos
Thank you for your kind words but I haven't tried this products.
I didn't find anything missing from the Diablo bass performance but mind you that it is a reference type presentation without added boost or enhanced performance.
That is that you get exactly what is in the recording and your headphone is able to do and can't further amplify it.

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