iFi audio Pro iDSD Digital Analogue Converter

Every section of the Pro iDSD has received massive attention to detail. Classic design techniques for very low-noise design found in tube equipment have been combined with cutting-edge, 21st Century technology to deliver a superlative performance.

Studio Grade Remastering DSD1024
For the first time, Pro iDSD brings Studio Grade DSD1024 remastering to the mass. Now one can remaster all his/her music to a superlative DSD1024 format just like in a recording studio and enjoy the ultra-high resolution it provides.

For the DSD1024, if the MultiBit DAC is one half of the ‘heart’ of the Pro iDSD’s digital engine, then the other half is surely the Crysopeia FPGA. This is where we believe FPGA excels, by handling the remastering duties to attain the DSD1024 audio format. In fact the Pro iDSD can handle all audio formats to to DSD1024 or DSD512 or PCM 768kHz with user-selectable digital filters.

Tube/ Solid-State Real-time Switching
Compared to high-end headphone amplifiers, the tube stage of the Pro iDSD is different in two-ways. First, we don’t use good-quality 6922s or similar. Instead we use the very best; General Electric 5670 which is the premium variant with a different pinout.

Second and just as important is the circuit design. Unlike other amplifiers that have the same circuit and just switch in/out the tube section, the Pro iDSD is the very first of its kind that has two individual input circuits – one tube and one Solid-State. This results in the best sonics of both worlds because the signal path is the shortest and there is no compromise to ‘shoe horn’ the tubes into an already existing solid-state circuit.

Quad Stack
The iDSD Pro uses a Quad ‘stack’ of iFi’s Bit-Perfect DSD and DXD DACs by Burr-Brown in a custom ‘interleaved’ configuration. This enables a total of eight pairs of differential signals to be used and mixed – four pairs of signals per channel.

All signals to the DACs are re-clocked with the low-jitter Global Master Timing® master clock derived from the AMR DP-777 DAC.

The DACs operate ‘Voltage Output Mode,’ giving >119dB dynamic range. All filtering is passive, using a fully-balanced third order capacitor/inductor/capacitor filter, rather than active, feedback-based circuits, to remove ultrasonic noise. (Active filters struggle with the amount of ultrasonic noise and RFI they have to handle and at a few 100kHz they can lose the ability to filter noise at all, which is precisely where a lot of noise is present.)

Using passive CLC filtering directly after the DAC means that the following analogue stage is not required to handle ultrasonic noise and RFI originating from the DAC process.

New XMOS Core
The Pro iDSD features the new XMOS XU216 X-Core 200 Series 16-Core processor,with a maximum of 2,000 MIPS (two billion instructions per second) calculation power in dual-issue mode as a USB interface.

All digital processing is Bit-Perfect, without employing ASRC or up-sampling unless digital filters are explicitly selected. A variety of digital filters (including Bit-Perfect mode without digital filtering) are available.

The Pro iDSD supports both USB 3.0 Type B connections and USB 3.1 Type C connections – a first for a DAC. All inputs (including USB) are galvanically isolated and the USB input is self-powered. The SPDIF inputs use technology derived from the AMR DP-777 including a new, solid-state implementation of the HD-VDi, memory buffer and the Global Master Timing® clock system.

Recording engineers please note that the Pro iDSD supports the AES3id-based DARS (Digital Audio Reference Signal) as recommended in the Audio Egineering Society’s published AES11 standard.

Wireless playback
With LINKPLAY™ WiFi/network playback, built-in Spotify and Tidal, and wide protocol support for 32-Bit/192kHz and DSD64, the Pro iDSD can directly link to a router for online music play. This gives it the option to: Play direct from SD card, Link to router and directly steam (TIDAL/MQA, Spotify etc) and Use DLNA via music stored on HDD

Power Supplies
Using classic tube design, brought up-to-date with 21st Century technology, all incoming DC is converted to a high-frequency waveform then rectified and filtered by a choke input capacitor filter. This produces a first-level DC bus from which all further voltages are derived. The circuit also generates a galvanically-isolated power supply voltage for the USB input circuitry.

The digital section is powered by a bank of Super Capacitors totaling 6.6 Farad (6,600,000uF). iFi uses Elna Dynacap DZ (TM) Super capacitors because they have a 400 times lower internal impedance than common grades of super capacitors.

Individual low-noise TI LDO Regulators with local LC filtering provide the final low-noise power for all individual digital sections, a total of six individual regulators cover Clock, SPDIF Input and the DAC’s digital section.

For the analogue stage (especially the tubes) higher voltages are needed. The whole stage effectively operates on a 60V rail offering massive potential dynamic range.