iFi Audio Pro iDSD discussion thread
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iFi audio

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I wonder how it's complicated to insert a digital output on a streamer ...
The iDSD Pro is a flagship DAC first, foremost and only. It integrates network audio bridge functionality to avoid needing an external streamer.

Not for the DAC, for the streamer.
The networking component is deeply embedded in the whole memory buffer/clock management of the iDSD Pro. It can't neither function in any sense in a stand-alone manner nor is it possible to provide a digital output from it without adding a lot of extra circuitry and reducing the integration between the actual DAC side and networking component, which would possibly impact on sound quality.

Again, the iDSD Pro is NOT a streamer that happens to have a DAC, but our TOTL DAC that includes networked sources as an input option, in addition to traditional inputs.
 
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post-13957074
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Alcophone

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I'm not talking of comparing but switching from one to another considering the wished sound. But I note that the iUSB 3.0 allows to replicate the usb signal for two connections.

I wonder how it's complicated to insert a digital output on a streamer ... You can find many streamers with both DAC and digital output and not very expensive for some of them :





I totally understand you haven't planned it but I'm a bit disappointed with that because that's so simple and useful.
This surprises me, too. The $200 iFi nano iDSD has a coax out, somewhat randomly. Why not this one? USB out is much harder, of course, that I would not expect.
 
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Will the istack pro be available?
 
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post-13958325
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This surprises me, too. The $200 iFi nano iDSD has a coax out, somewhat randomly. Why not this one? USB out is much harder, of course, that I would not expect.
iFi answered this two or so posts above yours:
  1. Post #1876 The networking component is deeply embedded in the whole memory buffer/clock management of the iDSD Pro. It can't neither function in any sense in a stand-alone manner nor is it possible to provide a digital output from it without adding a lot of extra circuitry and reducing the integration between the actual DAC side and networking component, which would possibly impact on sound quality.
 
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post-13959977
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Preview – Pro series - part 5/5
Jaw-dropping features - the story ends

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.

The USB input section has its own separate power management system with multiple regulators and filtering operating from the galvanically-isolated voltage generated to power this section.



For the analogue stage, higher voltages (especially for the tubes) are needed. The whole analogue stage in effect, operates on 60V rail, giving massive potential dynamic range. These are generated from the main DC Bus and filtered using multiple stages of inductor/capacitor filters, with Elna Silmic Capacitors forming the final stage.

Every section in the iDSD Pro has received massive attention to detail and combines classic design techniques for tube equipment with state-of-the-art technology to deliver extreme performance.

iDSD Pro Features

Sample Rates:
  • PCM up to 768kHz
  • DSD up to 24.576MHz
  • DXD and double speed DXD (2xDXD)
Studio DSD Remastering:
  • PCM 705.6/768kHz (from all PCM sample rates)
Crysopeia FPGA Digital Engine:
  • DSD 512/1024 (22.5792 - 49.152MHz) user-selectable
Inputs:
  • USB (required for DSD, DXD and sample rates above 192KHz)
  • Wifi – Linkplay
  • Ethernet – Linkplay
  • USB-Memory/Harddrive – Linkplay
  • SDHC Memory Card - Linkplay
  • AES3 (XLR - single link)
  • SPDIF (RCA/Optical combo)
  • BNC multifunction In (SPDIF/AES3id In, DARS In, 10MHz In, Atomic clock in
  • BNC multifunction Sync Out (DARS out, 10MHz out)
Outputs:
  • Balanced XLR at 4.6V (+15.5dBu - HiFi) or 10V (+22dBu - Pro)
  • Single Ended RCA at 2.3V (HiFi) or 5V (Pro)
  • Headphones 6.3mm & SE 3.5mm Jack at 2.3V, 5V or 8V maximum
  • Headphones BAL 3.5mm Jack at 4.6V, 10V or 16V maximum
  • Headphones out 1,500mW RMS X 2 @ 64 ohm, 4,000mW max. 2 X @ 16 Ohm
Volume Control:
  • Balanced (quad) Alps potentiometer, motorised with IR remote control
  • XLR/RCA outputs can be selected as fixed level or adjusted
  • 6.3mm Headphone Jack is always adjusted
Other Functions:
  • Various digital and analogue filters can be selected for DSD and PCM up to 192KHz
PCM Filters:
  • Bitperfect (no digital filter, minimal analogue filter)
  • 44.1 - 192KHz, always used for 352.8 - 768kHz
  • Bitperfect II (no digital filter, analogue filter corrects HF rolloff)
  • 44.1 - 96kHz
  • Minimum Phase (Filter has no pre-ringing and minimises post-ringing)
  • 44.1 - 384KHz, 32 Tap
  • Apodising (Filter has no pre-ringing and moderate post-ringing)
  • 44.1 - 384KHz, 128 Tap
  • Transient Aligned (Filter has extreme pre- and post-ringing)
  • 44.1 - 384KHz, 16384 Tap
  • additional fixed 3nd order analogue filter @ 100kHz
DSD Filters:
  • fixed 3rd order analogue filter @ 100kHz, compensation for 6dB level difference between DSD & PCM
 
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post-13960225
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EVOLVIST

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Preview – Pro series - part 2/5
Jaw-dropping features

1) Quad DAC section

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



While the iDSD Pro includes field programmable gate arrays (FPGA) for digital remastering duties – where we believe they excel – there are also external D/A sections, with a limited number of elements. In the iDSD Pro we use four interleaved 64-Element converters, to create a 256-Element DAC per channel, manufactured at high level of precision.

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


2) Studio DSD Remastering

Bit-Perfect or Upsampled

All digital processing is Bit-Perfect, without employing an Asynchronous Sample Rate Converter (ASRC), or by up-sampling unless digital filters are explicitly selected. A variety of digital filters (including Bit-Perfect mode without digital filtering) are available.
Thank you, iFi for all the new information. I've quoted this section - now that you've laid out all the features and we're a month away from release - to see if you can explain in more detail how the quad stack effects the SQ, and how this approach differs, or is superior, to your competitors? I mean, I really don't know, because everyone has their own way to skin a cat, and it seems that iFi is doing something different here. So, different, in fact, that I can't make heads or tails out of it. :)

With all of the different filters, obviously you included them because you believe there are different benefits for each. Concerning the filters, is this a matter of catering to those who want non-upsampled audio, as well as those who want to upsample?

Lastly, for going into the iDSD Pro via LAN, one is limited to 24/192 input, correct, but this still can be upsampled to what exactly? In other words, the iDDS Pro upsamples the data coming in via a LAN line to x times DSD?

Thank you for your time. It seems like a brilliant product!
 
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Is the headphone amplifier in this the same caliber as the micro black label/ican se or even better?
 
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Is the headphone amplifier in this the same caliber as the micro black label/ican se or even better?
It's second only to standalone Pro iCAN.
 
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post-13964840
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And it has both single ended and balanced out for headphones, is that right?
Single-ended 6.3mm, single-ended 3,5mm and balanced 3,5mm headphone outs. Three in total.

Except it won't have 3D or XBass of course. If you like those, stick to your BL
True, it won't have these.

Thank you, iFi for all the new information. I've quoted this section - now that you've laid out all the features and we're a month away from release - to see if you can explain in more detail how the quad stack effects the SQ, and how this approach differs, or is superior, to your competitors? I mean, I really don't know, because everyone has their own way to skin a cat, and it seems that iFi is doing something different here. So, different, in fact, that I can't make heads or tails out of it. :)

With all of the different filters, obviously you included them because you believe there are different benefits for each. Concerning the filters, is this a matter of catering to those who want non-upsampled audio, as well as those who want to upsample?

Lastly, for going into the iDSD Pro via LAN, one is limited to 24/192 input, correct, but this still can be upsampled to what exactly? In other words, the iDDS Pro upsamples the data coming in via a LAN line to x times DSD?
We'll be explaining all this gradually. In the meantime, digital filtering related part one is down below.
 
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The story about digital filters ...
... as we see it

Alright, let's be frank about one thing...

ALL FILTERS ARE WRONG. ALL OF THEM, INLUDING THE 'NO FILTER' OPTION.

The reason is that such rules like Nyquists's law sampling theorem are true, but are limited by strictures that make them not directly applicable to highly variant signals (e.g. music) which may contain content that can't be resolved into finite numbers of sine-wave wavelets.



Digital filters are based on steady state mathematics and thus distort the music signal, primarily in the time domain. This is an unavoidable byproduct of their function. Operating without filter distorts the music in a different way.

Many publications offer good reasons why a specific form of digital filter is superior. Usually the reasons are based on theory and in how close a given filter implementation comes to such a theoretical ideal.

What is commonly omitted and ignored are listening tests of radically different filters with different types of signals.

All digital filters (including non) differ in how they are wrong and how this influences objective measured performance as well as subjective listening performance with music and indeed specific music.



Music with a highly percussive nature and many instruments containing non-harmonic sounds (i.e. Jazz or Pop) will react different with a digital filter than music which is based mainly on pure tones and harmonics (i.e. a string ensemble plus a soprano singing).

These distortions become all the more relevant and carry greater possible audible consequences, the lower the sample rate. So the most abundant digital music source - CD quality - is most impacted.

Wherever there is a difference, there is also a preference. Subjective listening preference may be informed by a learned or acquired response to recorded sound (e.g. what sounds "right" or "hifi" is not what sounds natural in comparison to a live performance), in addition to direct referencing acoustic music performances.

So, no matter what single fixed filter is present, it is wrong and may not be preferred by a customer at least not with all music. What AMR implemented in the DP-777 (...and now iFi audio in the Pro iDSD) is to give a user a choice between the CORE possible approaches to digital filtering that we have found to produce meaningful differences and preferences in listening.



We offer the option to bypass digital filtering completely, to select minimum phase filters of differing structure (minimum ringing or apodising) or to select a "transient aligned" FIR filter that offer a maximally long filter response and number of taps to come closes to the idealised textbook filter.

Hence we do not prescribe ONE singular 'perfect' approach, we offer the choice between different approaches that have all been declared by their respective proponents to be 'perfect' and leave the choice which kind of 'perfection' is preferred to the customer.



Note, not everyone is sensitized to the differences digital filters make. Whatever your preference, simply choose what you like based on either what you believe to be right or on what sounds best to you. We do recommend to experiment with filters at least occasionally, especially once listening to different styles of music than usual.

Stay tuned, coming up is Pro iDSD's digital filtering!
 
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post-13964991
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EVOLVIST

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That's one thing I love about iFi; they are always honest in their approach. Very cool!

BUT! - if you keep rolling out data this slow, guys, then the release day will be upon us, and you'll have just wrapped up your explained features. :ksc75smile:
 
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