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iFi S/PDIF iPurifier: entry-level pricing, next-level results

  • “The Google Chromecast Audio is very easy to install, easy to use, very affordable and yet, wasted money as far as I’m concerned.” That’s The Netherlands’ Hans Beekhuyzen hitting us right between the eyes with his take on Google’s audio streaming puck.

    Beekhuyzen continues: “I know that ‘quality audio’ is a poorly defined qualification, that’s why I use my three reference sets. Already on my €900 set 3 the Chromecast Audio performed so poorly, both analogue and digital out, that there was no point in going to Set 2. The stereo image is completely squeezed together, instruments are no longer separate entities, it’s just one mash of sound.”

    Looking past an absence of gapless playback with Tidal and, to a lesser extent, Spotify, Beekhuyzen’s findings jive with my own. In all but the most basic of audio systems, the Google Chromecast Audio’s (GCA) optical output gets found out. The presentation lacks soundstage height, its bass definition is woolly and there’s clear evidence of top-to-bottom layer congeal. Mash potato, anyone?

    One might then point to the GCA’s US$35 price tag and ask “Where’s the beef?”. Answer: it’s a close-to-free lunch that isn’t.

    Of course, not everyone will necessarily hear it this way. As Chris Connaker wryly opined over at Computer Audiophile, “People who believe bits are bits and all digital audio must sound the same will be incredibly pleased with the Chromecast Audio.”

    If that’s you, time to alight here.

    A reader then stopped by DAR’s comments section to ask: “Are you saying that the GCA’s DIGITAL output has a “sound”? Or that it alters teh [sic] sound vs another digital output? What aspect of the TOSlink output do you feel is degrading the sound. It’s a direct digital connection to the DAC.”

    Indeed it is. I restated my observation that the GCA lacks separation and clearly defined spatial cues, implying (once again) that digital audio isn’t just a matter of ones and zeroes. They represent the beginning of the digital audio story, not the end.

    “But the connected DAC for the most part determines the sound yes? Do you suspect it’s jitter on the part of the CCA’s digital output perhaps?”, countered the reader.



    Jitter – the mis-timed arrival of those ones and zeroes – which may or may not be caused/compounded by electrical noise. The GCA is powered by a switch-mode wall-wart that makes no claim of the quiet life.

    Think that the galvanic isolation of TOSLINK is the answer. Think again. The way many a digital audio engineer tells it, electrical noise and/or jitter can blur the square wave to such an extent that the DAC’s receiver chip triggers additional layers of error-checking circuitry which then introduce more noise to the DAC’s sensitive internals causing disturbance to its super-sensitive clock and therefore more jitter.

    Whatever the theory, many a DAC manufacturer’s marketing department would have us believe that their J-word. Experience tells us otherwise. All other things (DACs) being equal and with a sufficiently resolving system, no two digital streamers perform / sound alike.

    For the aforementioned reader, for Hans Beekhuyzen and for yours truly, one freshly minted solution to the GCA’s lacklustre performance comes from AMR spin-off iFi Audio. Their S/PDIF iPurifier is a corrective appendage that promises to improve the sound quality of any S/PDIF restricted device, all for US$149. Is this the single most affordable S/PDIF re-clocker currently in production? I believe so.


    This story has been on hold since May when we first caught AMR/iFi mainman Thorsten Loesch and his S/PDIF iPurifier at Tokyo’s Fujiya Avic headphone festival. Back then, Loesch’s latest fingerbob had yet to go into full production but he had a prototype on hand to show off the unit’s twin-board internals.

    “With a Bill of Materials (BOM) that stands at 53 individual components, be assured that beneath its unassuming exterior, there are two separate PCBs, each mil-spec’d and packed to the brim with advanced technology”, runs the S/PDIF iPurifier’s promotional copy.

    The story goes like this: Loesch first took some of the S/PDIF input tech found in his high-end multi-thousand dollar AMR DP-777 DAC/pre and applied it to the more affordable iFi Audio product range, specifically the iDSD DAC and Stereo 50 ‘Retro’ system.

    Loesch later relocated those devices’ power rejuvenation and data re-clocking tech into a standalone device, the S/PDIF iPurifier, a thumb-drive sized dongle that plugs directly into the coaxial input of a DAC (a la Audiophilleo) or to a DAC’s TOSLINK input via the supplied optical fly-lead and mini-TOSLINK adaptors.

    This 5-minute video interview with Loesch fills in the blanks:

    I’ll confess to being somewhat unclear as to how exactly the sole coaxial input doubled as TOSLINK input until the review arrived last week: that coaxial socket’s centre hole also accepts a mini-TOSLINK plug. Clever.

    Nerd note: both coaxial sockets are audiophile-approved 75 Ohm. An adapter is supplied for conversion to BNC should you need it. So too are a pair of plugs that take a TOSLINK plug to mini-TOSLINK.

    The upshot? We’re covered for TOSLINK in and out, coaxial in and out, coaxial in and TOSLINK out and vice versa. Four options that point us to the iPurifier’s basic utility as a simple format converter.

    One might use this iFi dongle to route the coaxial-only digital output of the Devialet Expert 200 into the TOSLINK-only Devialet Dialog which in turn deals audio out to a pair of Phantoms. Extreme – but possible.


    As a S/PDIF re-clocker, the iFi device’s intent is to “restore the square wave” that journeys along coaxial or optical cables from streamer to DAC with the latter’s receiver chip must translate to ones and zeroes. By Loesch’s own admission, this iPurifier (there is also a USB version) nods in the direction of Genesis’ Digital Lens which, back in the late 1990s, sold for US$1800. This iFi pipe cleaner clocks in at one tenth of that. Progress!

    In targeting jitter and electrical noise, the iPurifier: 1) reclocks the digital audio signal; 2) galvanically isolates the source device (e.g. GCA) from the DAC; 3) takes its power from a low-noise 5V iPower SMPS (supplied); 4) specifies a Femto clock for superior timing of the bitstream as it leaves the devices internal buffer.

    Unlike Wyred4Sound’s more expensive Remedy which outputs 24bit/96kHz irrespective of the PCM input, the iFi dongle messes not with the bits. The absence of an internal sample rate converter (SRC) within the iPurifier sees 16bit/44.1kHz come in and 16bit/44.1kHz go out. That holds for all sample rates up to 24bit/192kHz PCM and DSD sent via DoP.

    (For those looking to iFi ‘correct’ DVD players or Blu-Ray spinners, Loesch’s S/PDIF contraption will readily parse Dolby Digital and DTS but these remain beyond the remit of this publication.)


    At first blush, the iPurifier almost seems over-specified for its intended target/s: mass market streamers and disc spinners. In this scenario, better to be overcooked than underdone.

    For the Google Chromecast Audio (GCA), digital audio file compatibility tops out at 96kHz but the majority of end users will be using it for cloud streaming from the likes of Spotify, Tidal, Google Play, Deezer, Mixcloud, Soundcloud or any other Google Cast-enabled app.

    Time to plug and play. Would the iFi S/PDIF iPurifier improve the sound of the GCA’s digital output? Does Grizzly Adams have a beard? Does a one-legged duck swim in a circle?

    Often it takes days, weeks even, to ascertain the qualitative differences between digital sources and sometimes, rarely, it hits us from the first push of play. One of those sometimes is now.

    With the iFi pushed directly onto the Peachtree Nova150’s coaxial input socket and fed Tidal HiFi streams by the GCA, the improvements to Nick Cave & The Bad Seeds The Boatman’s Call were immediate and obvious. The loudspeakers in use were the Spatial Audio M4 Turbo S.


    We’ll exemplify with the album’s second cut “Lime Tree Arbour”. With the iFi in place, bass notes took on better shape and definition, no longer lost to woolliness or obscuring organ sounds themselves, which in turn implies better separation.

    The piano motif that introduces us to the song’s second verse benefitted from a notable – i.e. not subtle – reduction in glassiness.

    Layer separation went up several clicks. Put another way, midrange congestion became less of an issue. This then brings us to the most obvious improvement heard from an iFi-spruced GCA: a MUCH taller soundstage.

    The S/PDIF iPurifier also improves player definition and location – a finding took more time to deduce as well as a cut over to a different source device: the 3rd generation Apple TV. With AirPlay on board the Apple slab can run as a 16bit/48kHz-restricted Roon endpoint; no biggie for Redbook rovers. As a solo player, the Apple TV’s underperformance with overall avidity was palpable. Here again, like the GCA, the iFi thingamabob brings a conspicuous improvement.


    Ditto the Sonos Connect which, with iFi correction applied, moves within a hair’s breadth of the AURALiC Aries Mini as digital streamer. Of course, the Sonos brick doesn’t do hi-res audio, nor will it host a USB-connected or internal hard drive. As an aside, the Aries Mini’s onboard D/A converter remains quite a bit better than that found in the long-toothed Sonos.

    Adding spice to this story is my final finding: the iFi S/PDIF iPurifier lifts even the Aries Mini’s S/PDIF game. The with/without delta isn’t as large as with GCA or ATV but it’s enough for the do-or-die optimiser to sit up and take notice.

    For those who would readily drop the same coin on a S/PDIF cable – there are many of us, let’s face it – this iFi is an easy call to make, if only to make the Google Chromecast Audio more pallettable.

    Thorsten Loesch’s latest device is as sharp-shooting as digital audio devices come. Readily discernible results for an easily digestible asking price. You cannot reasonably ask for more than that. DAR-KO Award, no question.


    Further information: iFi Audio


    Written by John

    John currently lives in Berlin where he creates videos and podcasts for Darko.Audio. He has previously contributed to 6moons, TONEAudio, AudioStream and Stereophile.

    Darko.Audio is a member of EISA.

    Follow John on YouTube or Instagram

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