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iFi audio xDSD- The Official Thread

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  1. rafaelo
    I guess this usb is for charging only. It seems it has DAC since it has a Bluetooth and maybe an IEMatch? It doesn't seem to have usb and spdif implementation.

    I am very curious to see if this a cheaper version or more expensive to xDSD.
  2. cardeli22
  3. ExpatinJapan
    monsieurfromag3 and gr8soundz like this.
  4. gatucho
    Yes I noted this one also, but it seemed too "plastiky". And besides it has no aptX HD support, as opposed to the xdsd which is all metal and supposedly did aptX HD.

    It was no contest. Well at least the metal part still is:rolling_eyes:
    cardeli22 likes this.
  5. gr8soundz
    xCan looks good; like an xDSD minus USB/digital inputs but with double the power, full balanced in/out, and adjustable xBass. Not sure about the switch to ESS chip though but nice that it retains bluetooth capability.

    If the xCan also has a line-out feature and can convert SE in to balanced out it may work as the balanced preamp/EQ I've been searching for. Hope the price is around the $2XX range? (or less; if so, could explain the change from BB chip to ESS).
    Last edited: Apr 28, 2018
  6. dannyvstheworld
    Anyone has experienced any Bluetooth connectivity issue? My unit stopped connecting to any devices in Bluetooth mode, after the 2nd or the 3rd time I restarted it. All established connections are lost, the device can't be found, and it won't enter the paring mode. All other functions look fine.

    Have already created a support ticket, but am wondering if there's a quick way to fix it. Thanks.
    RockStar2005 likes this.
  7. Jearly410
    I have one as well and it is a great device. Well worth $100.
    monsieurfromag3 and jeffhawke like this.
  8. Koolpep

    Are you using an iPhone by any chance? Because I have the same but not only with xDSD but also with my AK XB10 BT receiver sometimes the connections just disappears and I need to forget and anreconnect the device. Seems to be an iOS thing.
    RockStar2005 likes this.
  9. dannyvstheworld
    Thanks, but my xDSD neither can be selected on paired devices, nor can be seen on unpaired devices, and it won't even enter the pairing mode anymore, so it's probably not an iOS thing.

    Anyway I've already created the support ticket and expect some feedback pretty soon. I'm just a bit frustrated because it really sounded pretty good in the Bluetooth mode. It's times like these that you wish there were some restore to factory settings button.
    RockStar2005 likes this.
  10. iFi audio
    Mhm, something's goin' on!
    iFi audio Stay updated on iFi audio at their sponsor page on Head-Fi.
    https://www.facebook.com/iFiAudio/ https://twitter.com/ifiaudio https://www.instagram.com/ifiaudio/ https://ifi-audio.com/ info@ifi-audio.com
  11. ngoshawk
    A little light listening through the xDSD/64Audio U8/MBP to Dave Brubeck...not bad at all...

    Last edited: Apr 29, 2018
  12. iFi audio
    Yup, we believe so as well!
    iFi audio Stay updated on iFi audio at their sponsor page on Head-Fi.
    https://www.facebook.com/iFiAudio/ https://twitter.com/ifiaudio https://www.instagram.com/ifiaudio/ https://ifi-audio.com/ info@ifi-audio.com
  13. iFi audio
    Let's address the aptX HD in our xDSD. In short, this was a typo, xDSD doesn't do aptX HD. If anyone feels betrayed, offended, displeased, enraged, apologies to all such individuals for this situation, but...

    Let's talk Bluetooth!

    Some comments on X-Series Bluetooth. First, Bluetooth implementations vary widely. Just looking at BT revision level or codec support is not useful to understand sound quality potential of a given Bluetooth device.

    Yes, Sub Band Codec (SBC) is seriously hobbled and should not be used for music. A very extensive comparison of Bluetooth codecs (sadly excluding AAC) is found here:
    With aptX/aptX HD and AAC, optional codecs are available that perform better than SBC, however codec support is a fairly small issue.

    By default, most certified Bluetooth modules only offer analogue outputs, directly from the System On a Chip aka. SOC (CSR/Qualcomm in the upper end devices, others in the rest). To get a digital output for SOCs with that option available, a firmware needs to be changed (which is not trivial) and - because is changed in the process - any agency certification needs to be applied yet again, which costs a nice stack of cash.

    So most Bluetooth products rely on a DAC in a chip, to:
    • save money for an extra DAC
    • save money for firmware changes
    • save money for recertification process
    The problem is that a DAC/headphone amplifier inside Bluetooth chipsets is usually worse than DAC/headphone amps used in most headphones. For example, let's compare top rated CSR chipset's specs to audio test results of last iPhone with a headphone jack or Apple's lightning to 3.5mm adapter.

    With only 96dB dynamic range, aptX HD is wasted in such devices as these only support 16 bit audio on a DAC level and both objective and subjective audio performance from the SOC DAC/headphone amplifier is poor.


    To move on, in order to have higher quality Bluetooth audio, we need to bite the bullet and pay developers to enable digital outputs and THEN pay for the recertification of the module according to CE/EMC (European Union) FCC (USA), Giteki (JP) and KCC (Korea) etc. Now we can add an external DAC chip of higher grade.

    But hold it, we have another problem. Clocks. The typical Bluetooth SOC chip creates all clocks (those for audio as well) from a single 26MHz crystal via multiple PLLs of 'adequate' quality. The datasheet for the current 'Top of the Line' CSR chip (the only one that supports aptX HD) lists audio clock jitter as a maximum of 21,000pS in 'high quality' mode (more in power saving)!

    In order to deliver 16 bit audio without degradation, jitter must be below 243pS!

    So the jitter in the audio clocks actually precludes even 16 bit performance by being almost 100 times as large as the 16 bit limit as long as an external DAC (not the one in a Bluetooth chipset) includes means to clean up this jitter. The real performance will be degraded to only around 10 bit worth of actual audio performance.

    If a 'high end' version of a given system produces 100x the jitter permissible for 16 bit audio, effectively limits audio to 10 bit and barely manages 16 bit equivalent SNR with volume control maxed out (even where external higher grade DAC's are used, then Bluetooth associated with poor audio quality is a reputation well deserved.

    Noise and jitter levels in standard Bluetooth SOCs are comparable to the worst and darkest day of early digital audio, time when the understanding of what caused 'digital/artificial sound' was poor. The best external DAC will not solve this without extra effort spent on clocks.

    Let's get real now: the extra bits from aptX HD over aptX are not going help here, even aptX and AAC are probably mostly a wasted effort.

    In the xDSD we have the ultimate jitter fighting weapon on-board, in addition to our high quality DAC and a headphone amp, a super precise clock and memory buffer already applied to wired connections.


    All in all, squeezing the last drop of quality out of Bluetooth is not hard. After dealing with the wireless side, we simply take digital data from a system associated with it in the same way we treat USB and S/PDIF. And finally we get to a point where we can tell the different codecs apart (and aptX wins).


    In the xCAN it was more challenging to get a subsystem to get excellent sound from Bluetooth. We naturally can't fit a full xDSD level circuitry and that's why we cherry-picked ESS Sabre instead of Burr-Brown.

    We feel that using the ESS Time Domain Jitter Eliminator to kill the jitter from the Bluetooth SOC is decisive in getting excellent sound quality. The reference clock for the ESS DAC is produced from a discrete oscillator with its own low noise power regulator.


    Swap in Burr-Brown (as excellent as it is in our xDSD), run it on Bluetooth clocks and the sound quality suffers severely.

    The result of these efforts is a level of sound quality from Bluetooth for both xDSD and xCAN that is not comparable to the majority of Bluetooth products.

    And yes, adding aptX HD and even LDAC more than aptX HD (as the extra bits of aptX HD are not very useful whereas the 96kHz maximum supported sample rate of LDAC is) would make sense for xDSD and xCAN. However, it requires a substantial R&D time and was not possible for this year's release cycle.

    And lastly, slides used in this post were extracted from the Tokyo Headphone Festival presentation by iFi audio, already published by headpie.net at:

    Last edited: Apr 30, 2018
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  14. SteveOliver
    @iFi audio Thank you for the excellent explanation and for clearing the Aptx HD thing up.

    It all makes sense now, I hadn't realised that the Bluetooth SOC didn't include some kind of good quality digital output to feed directly into the DAC as standard.

    This makes me want to get an xDSD to test the Bluetooth input now. :)
  15. jeffhawke
    There is nothing like having clear ideas to explain them clearly! Thanks for the heads-up on the clock/jitter issue, which is obviously far more important in terms of its impact on the audio output than the difference between aptX and aptX HD. The one big question I still have now is: am I going to get the xDSD or the xCAN? :ksc75smile: If I understood correctly, the xCAN also does a digital-to-analogue conversion, but only for BT through the dedicated Sabre chip, is that right?
    Last edited: May 1, 2018
    cardeli22 likes this.
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