iFi iDSD Diablo Review

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.

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.

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.

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.

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.

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.

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.

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.

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.

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)

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