iFi's iDSD Diablo reference portable DAC/headphone amp is dressed in devilish red and, like a lightweight, high-performance sports car, kicks the non-essential features, such as sonic tailoring options and Bluetooth connectivity, to the curb. Instead, the focus for the ultra-high-quality circuit components here is pure sonic power, and the ability to drive any headphones. All you need to do is connect your digital source via USB or S/PDIF, plug in your headphones and hold on.

DIGITAL

It's no surprise to see the iDSD Diablo's digital stage employing a Burr-Brown DAC chip. iFi seems extremely fond of the chip's 'musicality', and True Native architecture enables PCM and DSD to take separate pathways. In the iDSD Diablo, there's a brace of chips working in a custom 'interleaved' configuration. We're told that this enables four pairs of differential signals (two pairs per channel) which apparently lowers the noise floor, improves channel separation and enhances the DAC's ability to resolve fine musical detail and micro-dynamics.

As well as the DAC chip, the iDSD Diablo also boasts a new low-latency XMOS microcontroller to take up information from the USB and S/PDIF connections. 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, states iFi.

Naturally, the XMOS firmware has been optimised by iFi's in-house digital development team. 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.

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. Additionally, there's full 'three-unfold' decoding of MQA files up to 384k.

ANALOGUE

iFi hasn't neglected the analogue side of things as it continues to introduce fully balanced circuit design across its range. 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 - dubbed PureWave by iFi.

The iDSD Diablo is designed to deliver reference-level sound and promises to drive all manner of headphones with ease. Ensuring this the portable DAC/amp delivers up to 5000mW, which should keep anything from sensitive in-ear monitors to current-hungry planar headphones, well-fed.

Tailoring the requirements of different headphone/earphone types is achieved via a trio of power and gain settings. '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.

UNDER THE HOOD

As has become expected, iFi has not skimped on high-quality components in the make-up of the iDSD Diablo's circuitry. Another critical 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 noteworthy is the use of a high-quality analogue potentiometer to control volume.

'Negative feedback' is used in amplifier circuits to compare the output signal with the input signal and correct errors to control gain and reduce distortion. Recognising that different parts of a circuit benefit from specifically optimised feedback loops, iFi has developed a negative feedback system that they say is much more accurate than the usual approach. Incorporating multiple feedback paths instead of one global loop, each path is optimised for a particular function and working synergistically with the others to deliver optimal overall performance. iFi calls this new configuration OptimaLoop.

Battery power provides a theoretical performance advantage over mains power. However, there are potential sonic downsides to battery power, resulting from low output voltage and inconsistent output impedance as the batteries discharge. Of course, iFi states that these side-effects have been tackled by the iDSD Diablo's design.

For instance, planar magnetic designs require the voltage to be stepped up from 3.7V to +/- 15V. This is achieved via 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 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, favouring 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.

DRIVE-THROUGH

Along with a standard 6.3mm single-ended headphone socket, you'll also find a 4.4mm Pentaconn output for headphones offering balanced connection at the front of the unit. 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 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. 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.

ROAD TRIP

iFi has bundled in its iPower 5V AC/DC adapter for mains power. This accessory 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 and 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.

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 degrade sound quality over USB. It all adds up to a package of accessories worth around £300.

iFi's iDSD Diablo is available from selected retailers from Friday 15th January at an RRP of £899.

Visit iFi Audio for more information