Lewis CaliburnNew from iFi is the DSD Diablo 2 premium-level portable DAC/headphone amp.
The iDSD Diablo 2 has been thoroughly redesigned inside and out, building on the performance-tuned design philosophy of its predecessor’s amp stage with technical advances across the board.
Its versatility has been enhanced too; while the original Diablo focused solely on cable connectivity from the source device – be it a PC or a Mac, a smartphone or a tablet – the Diablo 2 adds the latest generation of iFi’s famous Bluetooth engine, complete with aptX Lossless support.
According to the manufacturer, this makes it the world’s first portable DAC/headphone amp capable of processing lossless Bluetooth audio.
The iDSD Diablo 2 is similar in size to the original – 166x85x28.5mm – and while its size is similar to its predecessor and its aluminium enclosure still coloured red, it sports a new grooved design dressed in a new shade of metallic crimson. The 22 grooves are not just for show; they aid thermal dissipation and double as fixing rails for the ‘wings’ supplied with the iDSD Diablo 2. These detachable appendages act as a desk stand and can be positioned in different ways, allowing the Diablo 2 to be placed horizontally or vertically as its owner prefers.
The iDSD Diablo 2’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.
Whilst intrinsic to the resulting sound, the creation of a digital stage involves much more than the selection of a particular DAC chip. One such critical component is the XMOS chip that iFi uses to process audio data received over the digital inputs. The iDSD Diablo 2 incorporates a 32-bit, 16-core XMOS Cortex microcontroller, its processing power utilised by iFi to optimise sound quality and unlock the full potential of the BurrBrown DAC chip.
Extensive jitter-eradication technologies are also applied, including the latest version of iFi’s GMT (Global Master Timing) femtosecond-precision clock and smart storage cache. This combination of technologies forms the basis of a proprietary ‘digital engine’ that is unique to iFi.
Every format at the highest quality Hi-res audio support is state-of-the-art, handling PCM data to 32-bit/768kHz and all levels of DSD to 22.5792MHz (DSD512). 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.
MQA – the hi-res streaming technology as used by Tidal’s ‘HiFi Plus’ tier – is supported, with full decoding/upsampling of MQA files right up to the format’s highest 384kHz specification. Full decoding 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’.
iFi has now redesigned its Bluetooth module to further elevate its performance, and the iDSD Diablo 2 is the first portable device to include it (hot on the heels of the larger, mains-powered NEO iDSD 2). The headline addition for this next-generation iFi module is aptX Lossless – the first ‘lossless’ Bluetooth audio format.
While other Bluetooth formats described as ‘hi-res’ already exist – for example, aptX Adaptive can stream audio up to 24-bit/96kHz and LDAC’s specification stretches up to 32-bit/96kHz – these are ‘lossy’ formats. That means they compress the file by removing audio data that is considered less important to the end result.
These ‘hi-res’ Bluetooth formats apply compression that is more efficient and less audibly detrimental than older codecs, but sound quality is still compromised. aptX Lossless is the first Bluetooth audio format capable of streaming CD-quality (16-bit/44.1kHz) audio ‘losslessly’. Technically it still applies a form of compression, but it ‘zips’ and ‘unzips’ the audio file in a way that preserves the original data. It achieves bitrates of up to 1.2Mbps at CD-quality – that’s more than twice the maximum bitrate of aptX Adaptive and aptX HD, and roughly 20% higher than LDAC’s maximum figure.
aptX Lossless is part of Qualcomm’s Snapdragon Sound platform. To benefit from the format, both the source device (perhaps an Android smartphone) and the receiving device (Bluetooth headphones or earphones, a DAC or an audio system) must incorporate a suitably equipped Snapdragon chipset.
iFi’s NEO iDSD 2 was the world’s first DAC to include aptX Lossless decoding; the iDSD Diablo 2 becomes the first portable DAC to do so, benefitting from iFi’s close collaboration with Qualcomm to ensure the format’s benefits are maximised. In addition to aptX Lossless, a full suite of Bluetooth formats is supported, including aptX Adaptive (backwards compatible with aptX and aptX HD), LDAC, HWA/LHDC, AAC and SBC. This means that every source device is covered at the highest resolution its Bluetooth specification allows.
iFi’s Bluetooth module can also be updated over-the-air, so further codecs may be added as they emerge in future. As well as being the first portable DAC to support aptX Lossless, the iDSD Diablo 2 is the first to include Bluetooth version 5.4 – the newest Bluetooth standard, announced earlier this year. This reportedly ensures “the greatest wireless range and stability, highest speed and lowest latency” between the source device and the DAC. The Diablo 2 stores up to eight paired Bluetooth source devices in its memory, making it easy to switch between them.
Since launching the Pro iCAN headphone amplifier in 2016, iFi has gradually introduced balanced circuit designs of various levels of sophistication across its range. The original iDSD Diablo introduced a new twin-mono topology, fully balanced from input to output – iFi calls this level of circuit design ‘PureWave’, referring to the sonic purity it achieves thanks to exceptional linearity and infinitesimally low levels of noise and distortion.
PureWave circuits are sophisticated in design and implementation, incorporating premium quality components, and are therefore reserved for the upper tiers of iFi’s DAC and amplifier range. The iDSD Diablo 2 features the latest generation of iFi’s PureWave design, further enhanced to elevate audio quality and headphone amp power. Able to drive all manner of headphones with ease, from highly sensitive in-ear monitors to current-hungry planar headphones, the iDSD Diablo 2’s amp stage delivers power and “engaging dynamics”, coupled to an ability to resolve fine texture and detail.
With output power of 5,180mW/12.9V into 32 ohms and 611mW/19.2V into 600 ohms through its 4.4mm balanced output, the Diablo 2 has more power to drive the toughest headphone loads than any other portable DAC/headphone amp on the planet, claims the manufacturer.
The amp stage supplies three gain settings to suit the drive requirements of the connected headphones or IEMs. The default mode is Normal (0dB); from there users can step up to Turbo (+8dB) or Nitro (+16dB). There is also an IEMatch attenuation mode – this is particularly useful with super-sensitive IEMs, removing potential background noise and increasing the usable volume range. Volume is controlled by a high-quality analogue potentiometer, which delivers superior sonic transparency compared to chip based volume controls and can be locked in place to avoid accidental adjustment.
High-quality components are used throughout the iDSD Diablo 2’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 silk fibre electrolytic Elna Silmic II, aluminium-polymer Panasonic OS-CON, and multilayer ceramic types from Murata and TDK.
Another important aspect is the iDSD Diablo 2’s direct-coupled circuit design, achieved without a conventionally applied DC servo – iFi calls this design Servoless Direct Drive.
iFi has developed a negative feedback system that it claims 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. Developed for the original iDSD Diablo and further refined for the Diablo 2, iFi calls this configuration OptimaLoop.
To enable the iDSD Diablo 2’s amplification and a long life between charges, a 4800mAh lithium-ion battery is built in. The Diablo 2 can also be used when connected to the mains via the bundled iPower 2. This AC/DC adapter contains active noise cancellation circuitry that benefits the Diablo 2’s sonic performance when powered by mains electricity.
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 using 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.
Excelling with xMEMS xMEMS is a new solid-state micro-speaker technology which utilises a micro-electromechanical systems (MEMS) manufacturing process that blends semiconductor technology with moving parts. A silicon diaphragm combines with a piezoelectric layer, creating a tiny speaker capable of phase and transient response far superior to conventional moving-coil drivers, with high-frequency fidelity. xMEMS micro-speakers are voltage-driven, rather than current-driven, which means they have special requirements of an amplifier.
This technology has transferred to the next-generation iDSD Diablo 2, with bias voltage, EQ and amp circuits dedicated to make the most of headphones/earphones that use xMEMS drivers.
As well as wirelessly over Bluetooth, source devices such as PCs/Macs, smartphones, tablets and other digital entertainment devices can connect asynchronously to the iDSD Diablo 2’s USB-C port (certified to 5 Gbps). A 3.5mm S/PDIF input is also provided; this accepts both coaxial and optical connections (a 3.5mm to Toslink adapter is supplied).
Balanced analogue outputs are supplied, making the most of the iDSD Diablo 2’s fully balanced PureWave circuitry.
Along with the ultra-low-noise iPower 2 AC/DC adapter and associated USB-C charging cable, three digital audio cables are supplied: a USB-C OTG cable for smartphones and other portable devices, a longer USB-C cable for PCs/Macs and a Lightning to USB-C cable for iOS devices equipped with Apple’s proprietary connector.
Various adapters are included for different connector types: USB-C to USB-A (to connect the USB-C cable to source devices with USB-A outputs); 3.5mm to Toslink (to convert the iDSD Diablo 2’s S/PDIF input to Toslink optical); and a 3.5mm to 6.3mm headphone adapter.
The wing-style appendages that serve as a desktop stand are also supplied, together with a premium-quality travel case to protect the Diablo 2.
The iDSD Diablo 2 is available from selected retailers now at an RRP of £1,299.