The Devil in the Detail
Pure Sonic Performance
The iDSD Diablo, with its sleek new design and fiery red finish, sits proudly at the top of our range of portable/transportable DAC/amps. It is built for purists – the true headphone enthusiasts who crave pure, unadulterated sonic performance.
Just like a racing car designed for uncompromising speed, the iDSD Diablo sets aside sonic tailoring as well as Bluetooth connectivity to focus on pure sonic power. Prepare for a riveting ride as it will drive any headphone on the planet with aplomb.
Put simply, the iDSD Diablo is our best ever transportable amplifier designed to deliver reference level sound.
We use 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’.
And with MQA now available over S/PDIF, you can take advantage of any MQA CDs in your collection.
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 our balanced, symmetrical dual-mono topologies with short, direct signal paths. We call this PureWave.
Negative feedback is used in amplifier circuits to compare the output signal with the input signal and correct errors. BUT there are drawbacks. iFi turns the negatives into positives with OptimaLoop.
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 or track day supercar!
- Turbo – ramps up the level of drive for current-hungry headphones
- Normal – for most over or on ear headphones
- Eco – dials down the power to suit high-sensitivity in-ear monitors
Power that does not corrupt.
The iDSD Diablo’s focus on pure, unadulterated performance, means much attention has been applied to the power supply circuity.
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. We 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.
Formula 1, iFi style.
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 multi-stage filtering, and the microprocessor control circuitry (often a local source of digital noise) has separate regulation, too.
Crucial components for maxed out performance, more below.
Hooking up with the Devil…
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 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 Pentaconn balanced output to connect to an external amp.
As befits a reference-level product, we’ve included a whole host of accessories in a luxurious travel case.
As the iDSD Diablo may be powered from the mains, as well as by its built-in battery, we’ve included our super silent, noise-cancelling iPower 5V AC/DC adapter to ensure optimal sound quality.
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.
We’ve also added 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.
The Burr-Brown True Native® chipset means file formats remain unchanged or ‘bit-perfect’. This means you are listening to music as the artist intended in the format in which it was recorded.
At iFi we use Burr Brown extensively in our products having selected it for its natural-sounding ‘musicality’ and True Native architecture. Our experience with this IC means we know how to make the most of it.
The XMOS 16-Core chip processes the audio data received via the USB and S/PDIF digital inputs.
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.
MQA (Master Quality Authenticated) is 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. It is available through for Tidal Masters, Audirvana and Roon.
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.
PureWave is a new, balanced, symmetrical dual-mono topology with short, direct signal paths. The name refers to the sonic purity it achieves thanks to exceptional linearity and infinitesimally low levels of noise and distortion.
‘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 also highlight different problems at the same time as solving others – corruption of the error signal, phase shifts, group delay and so on can all have a negative impact on sound quality.
We recognised that different parts of a circuit benefit from specifically optimised feedback loops and have developed a negative feedback system that is much more accurate than the usual approach. This incorporates multiple feedback paths instead of a global loop, each path optimised for a particular function and working synergistically with the others to deliver optimal overall performance.
Extensive jitter-eradication technologies are applied to the digital stage, including our 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.
An important aspect of the circuit design is its direct-coupled nature (no coupling capacitor is present), achieved without a conventionally applied DC servo.
DirectDrive® equals a direct signal path which means less signal degradation. This direct signal path is unequalled in audio and is the reason why the sound is so ‘true’.
As with many other iFi audio products, we’ve incorporated a custom OV Series operational-amplifier. This top-notch component contributes to the extremely low noise, low distortion (0.0001%) and wide bandwidth.
Switching between settings has been engineered to ensure sonic transparency with advanced trench technology MOSFET is used as a muting switch.
This FET-based switching is handled by a micro-controller, which only ‘wakes up’ when the user changes a setting, thus eradicating any sonically deleterious interference.
TDK C0G (Class 1 ceramic) capacitors offer high stability and low losses for resonant circuit applications.
Getting ever closer to the theoretical ideal of pure, frequency-constant capacitance, these capacitors reduce capacitor-induced distortion to vanishingly low levels.
They are pricey but are a perfect addition to our products.
Panasonic OS-CON caps totaling 5,410uF give very-low Equivalent Series Resistance (ESR), excellent noise reduction capability and frequency response characteristics. In addition, OS-CONs have a long-life span and its ESR changes little even at low temperatures since the electrolyte is solid.
They are not often found in products costing <US$1000.
Vishay MELF resistors – complex, costly but superior.
These metal electrode leadless face resistors have excellent accuracy, stability, reliability, and pulse load capability. They provide optimal power rating and pulse load capability. They show some of the lowest noise and distortion of any resistor available in the market, period.
muRata control-type, low-ESR high-Q multi-layer capacitors. The ‘ESR control’ aspect of the Murata is something special. Their noise suppression abilities are impressive.
Texas Instruments low-noise ICs offer great unity-gain bandwidth, very low noise and distortion, high output drive capability, Common-mode and Power Supply Rejection Ratios of over 100 dB, wide maximum-output-swing bandwidths and high slew rates.