Incoming DSD files are also played in Bit-Perfect (BP) mode, except when the DSD Remastering option is chosen. In that case, DSD files are directly converted to 16 X PCM files inside the Crysopeia FPGA, then filtered using one of the options available at 16 X PCM, and finally modulated into high-res DSD512 or DSD1024. What’s fascinating about this process is that you start out with DSD files, convert them to upsampled PCM format so that you can apply the digital filters of your choice, and then converted back into high-res DSD for playback. Note that incoming DSD files at DSD256 or higher levels are always played in Bit-Perfect mode without remastering. The Pro iDSD can move between PCM and DSD file formats with the greatest of ease.
Thanks to a built-in WiFi antenna, and available Ethernet and host USB input sockets, the Pro iDSD can effectively function as its own server or streamer, which can be controlled by the third-party Muzo App, which is available for most popular Apple and Android smartphones and tablets. The Pro iDSD also offers built-in Spotify and Tidal applications, which again are accessed through the Muzo App. Plainly iFi has packed a tremendous amount of flexibility and numerous connectivity options within the Pro iDSD’s deceptively compact half-rack-width chassis.
Because iFi’s Pro iCAN headphone amplifier/preamp and Pro iESL electrostatic headphone adaptor module preceded the Pro iDSD in the marketplace, the natural temptation is to think of the Pro iDSD as the DAC that completes the Pro-Series product suite. However, there’s really more to the Pro iDSD story than that, because it is also a highly accomplished headphone amp/preamp in its own right.
Much like the Pro iCAN, the Pro iDSD’s amplifier section offers three front end configurations: a JFET-based solid-state front end, a General Electric 5670-based valve-powered front end (simply called “Tube” mode in iFi terminology) with low distortion and a moderate amount of negative feedback, plus a relatively low loop-gain/low negative feedback valve-powered front end option (called “Tube +” in iFi speak) that trades slightly higher distortion levels for more pure valve character in the sound. The main amplifier circuit is, says iFi, fully discrete and fully balanced with a “bipolar second stage and MOSFET-buffered bipolar output stage.” Levels are controlled by a 6-track, motorised ALPS rotary volume potentiometer. Power output, though lower than that of iFi’s potent Pro iCAN headphone amp, is nevertheless a very healthy 1500mW @ 16 Ohms (single-ended) or 4000mW at 16 Ohms (balanced).
Premium quality parts are used throughout the Pro iDSD’s audio signal path and power supply sections. For example, the Pro iDSD’s analogue section uses audio-grade Elna Silmic capacitors located, says iFi, “within a few millimetres of the audio circuitry supplied.” In turn, the digital section features a bank of Elna Dynacaps DZ™ ‘Super Capacitors’ collectively offering an impressive 6.6 Farads of capacitance. The capacitors are said to have “400 times lower internal impedance than common grades of super capacitors,” meaning they, “release energy much faster than other super capacitors.” Finally the power supply for the digital section uses six individual TI LDO Regulators with local LC filtering to “provide the final low-noise power for all individual digital sections,” including the clock, S/PDIF input, and the DAC’s digital section. In short, iFi backs up its high-end performance claims with the sorts of high quality parts one might expect to find in far more costly audio components.