iFi Announce Micro iDSD Signature Edition

Since launching in 2017 as an upgraded version of the original micro iDSD, the micro iDSD Black Label has been iFi’s top-of-the-range battery-powered DAC/headphone amp. The new Signature edition builds on its predecessor’s reputation for exceptional sound quality and versatility with enhanced circuitry in critical areas and a new 4.4mm Pentaconn headphone output, among other upgrades.

Digital Engine

The micro iDSD Signature’s ‘digital engine’ is based around a Burr-Brown DAC chip that iFi uses extensively, selected for its natural-sounding ‘musicality’ and True Native architecture. Here, as with the previous Black Label version, two of these DAC 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.

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. MQA ­– the hi-res streaming codec, as used by Tidal’s ‘Masters’ tier – is also supported. Thanks to the Burr-Brown chip’s 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.

Extensive jitter-eradication technologies are applied to the digital engine, including iFi’s GMT (Global Master Timing) femto-precision clock and intelligent memory buffer. The micro iDSD Signature also comes with iFi’s GTO (Gibbs Transient Optimized) digital filter installed; alternative digital filters can be loaded as firmware updates if preferred.

Circuit Training

The outgoing micro iDSD Black Label’s amp stage remains widely recognised as the finest available in any battery-powered portable DAC/headphone amp, able to drive all manner of headphones with aplomb, from highly sensitive in-ear monitors to current-hungry planar headphones. For the new Signature version, the circuitry has been fine-tuned – it still delivers the same prodigious power (up to 4100mW) and dynamic ability, but the signal path has been refined to maximise sonic texture and detail.

High-quality components are used throughout the micro iDSD Signature’s circuitry, utilising its larger form factor in comparison to pocket-sized DAC/amps. Custom ultra-low-distortion op-amps feature in both the digital and analogue stages (part numbers OV2028 and OV2627 respectively), together with a hand-selected range of capacitors including the multilayer ceramic type TDK C0G, polyphenylene sulphide film type Panasonic ECPU and aluminium-polymer solid 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 then 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 circuit design is its direct-coupled nature – no coupling capacitor is present. This is achieved without a conventionally applied DC servo; iFi calls this design Direct Drive Servoless.

Versatile Sonic Tailoring

With the huge variety of headphones and digital music platforms available, all with different technical characteristics, the ‘one size fits all’ approach offered by many DAC/headphone amp manufacturers fails to deliver the versatility many users require to make the most of their music. iFi designs its products to be more flexible, delivering precision sonic tailoring via switchable settings to match any headphone set-up, the variation in quality of digital audio files and, of course, personal taste – the micro iDSD Signature offers this versatility in spades.

The digital stage benefits from a variety of filter settings: ‘Standard’, ‘Minimum Phase’ and ‘Bit-Perfect’ for PCM files, and ‘Standard Bandwidth’, ‘Extended Bandwidth’ and ‘Extreme Bandwidth’ for DSD. The amp stage also has three settings to adjust power and gain: ‘Normal’, ‘Turbo’ (ramps up the level of drive for current-hungry headphones) and ‘Eco’ (dials down the power to suit high-sensitivity in-ear monitors and/or extend battery life).

Further optimisation for sensitive in-ear monitors – an area of weakness for many DAC/amps – is supplied via iFi’s IEMatch technology, which adjusts the output level to suit. Once engaged, two levels of IEMatch are available ­– ‘High Sensitivity’ and ‘Ultra Sensitivity’.

Those familiar with iFi headphone amps will recognise the company’s XBass+ and 3D+ settings. These proprietary circuits have been performance-tuned for the micro iDSD Signature and may be switched in or out according taste, fine-tuning the sound in the analogue domain to maintain sonic purity. XBass+ adjusts frequency response to enhance low frequencies – useful with ‘bass-light’ headphones, such as some open-back designs. 3D+ compensates for the ‘in-head localisation’ effect that often occurs when using headphones to listen to music that was mixed using a pair of speakers, effectively widening the headphone soundstage to deliver a more speaker-like experience.

At the back of the chassis lie two digital audio inputs: USB Type 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 Type A USB input features a ‘male’ connector, rather than a typical ‘female’ port. This arrangement provides greater mechanical integrity than the USB/Micro USB ports commonly found on DAC/headphone amps from other manufacturers. 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.

The iFi micro iDSD Signature will be retailed at $649 and is available for pre-order at Audio 46.

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