[Triodemode]

  No, You can play native DSD files with DoP encapsulation or without. Not all DSD DAC's can play DSD files natively without going to a PCM stage. 

So, DSD data must be carried inside a PCM frame using an ASIO driver when transferring via USB, and this is where the acronym DoP comes from?
 
I have a bit to learn coming from the analog world of vinyl.  Thanks for the assistance john57.

 

[BillsonChang007]

FWIW, I actually prefer the micro iDSD amp to the Asgard 2. I really enjoy the 3D and xbass effects on my HE500s and I've actually found several schiit products, the Asgard 2 included, to be slightly grainy/dry. I love the ifi products for their smooth detailed sound and in this case I prefer their mobile amp to schiits class A desktop amp... Go figure. Don't get me wrong, Schiit makes some great gear, and the Asgard 2 is a very good amp, but I'm on the micro iDSD train for the time being.

 
 

  +1.
 
while the iFi micro iDSD amp doesn't present the widest soundstage amongst SS amps I'd bet, the musicality, natural/realistic detail and presentation are just amazing.
regardless of the form factor, this is one SS amp that will keep me satisfied for sure.  even with IEMs and NAD HP50.
 
Lyr 2 with HE-560 and Vali keep my tube-sounding appetite fed.
variety is the spice of sound.

Thanks guys! What would be a perfect upgrade from the Micro iDSD's amp section then? Now I am looking at Micro iCan haha

 

[audioholik]

 
So, DSD data must be carried inside a PCM frame using an ASIO driver when transferring via USB, and this is where the acronym DoP comes from?

 
No, that's why there's no pop during DSD playback via ASIO (ASIO has native DSD support, no DoP required)... as an added benefit ASIO also bypasses Mac's inferior Core Audio infrastructure.
 
BTW, on its website, iFi Audio recommends using ASIO for "the best sound."

 

[iFi audio]

DSD DoP compared to ASIO native

 
There is a lot of mis-information tripping readers up - causing all sorts of odd interpretations and a little obfuscation!

 
Here is our explanation.

- ASIO native and DoP are two different ways to send DSD data through the USB Audio Subsystem.

 
- Both require Hardware support (in the DAC) and Software support (in the Playback software).

The key difference is that ASIO has its own distinct protocol that packs 32Bit worth of DSD data into a PCM sample but support even on Windows is very limited and does mostly not exist on Apple & Linux.

Contrastingly, DoP is totally platform/device/driver agnostic but can only transmit 16 Bit worth of DSD data per 32 Bit PCM sample (the rest is used up by the protocol marker and other overheads). 

So ASIO 88.2KHz native can transmit DSD64 while on DoP it needs 176.4KHz to transmit DSD data. Other than that fundamentally the two systems are very similar. Neither transcodes DSD into anything else, both use PCM Packets as "transport" and both re-assemble the original DSD datastream completely transparent and Bit-Perfect before it is sent to the DAC.


DoP "PoP" and how JRMC gets around this

The problem is that when DoP stops there is no defined "level". After DSD playback via DSD finishes, the DAC output may be at any given of 64 Levels and as no more data is send it will stay there.

 
There is a 1 in 2 chance that the level the DSD DAC outputs is either more negative or more positive than nominal "maximum music level". There is a 3 in 4 chance that the level that remains at the output of the DAC is greater than half the peak level of the Music.

When then PCM Playback starts it starts with silence (empty samples as no data is yet sent).

This empty sample forces the DAC to output 0V. This happens so fast, there is no way to mute this. The DoP Playback has already stopped and PCM is being send while we are still trying to get the mute on.

 
This is the "big pop", it is simply an instant return from X (where X will have a very high chance of being at a very high level respective to the music, positive or negative) to zero.

The way to avoid (or at least substantially reduce) this is click is to play some extra DOP Samples (we are unable to determine exactly how many J-River actually adds as they are able to virtually eliminate this issue) representing silence after the nominal playback is finished. By playing silence the DAC output will return to Zero, so when PCM kicks in it will be at zero or very close, so we get no or a very small click.

The ASIO implementation of DSD incidentally takes care of that and hence has no click. In the case of other DAC Chips that convert DSD internally to PCM before filtering and playback this whole issue obviously does not happen!

 
As so far they represent 95% or more of all DSD DAC's out there, this problem is hence quite rare.

We hope this sheds more light on this matter.

 

[iFi audio]

Also, any iCLUB members who are planning to attend the National Audio Show at Whittlebury Hall, please contact your concierge so that we can meet you at the show in the Headzones area!

 
Date: 20-21 September
Location: Whittlebury Hall (near Silverstone). UK.

 
More information here:
http://ifi-audio.com/audio_blog/eisa-award-3-5mm-ribbon-cable-giveway-at-national-audio-show/

 

[bms44974]

@Triodemode: The acronym DoP stands for "DSD Audio over PCM Frames". A description of the packaging details can be found here: http://dsd-guide.com/dop-open-standard.
 
The DoP standard (2012 v1.1) recognizes that, because the first 8 bits of each packet are used to identify the packet as DSD, there can be a pop when the packet is incorrectly interpreted as a PCM packet. When implemented according to the standard, an incorrectly identified PCM packet containing DSD data should result in "a tone around 88kHz and roughly -34db, nothing harmful and something that most D/A converters would suppress to some degree before it even reaches the loudspeaker." 
 
Disclaimer: your results may vary

 

[Triodemode]

Thank you for the excellent schooling by the gurus at iFi regarding the whole DoP and ASIO with DSD...   Just to confirm, ASIO and DoP both require PCM as a transport mechanism for DSD over USB correct? 
 
So when my Foobar2000 is setup using the 'foo_dsd_asio' driver with DSD selected as ASIO driver mode in the SACD plugin, is this why I am not hearing any pops when starting and stopping DSD tracks or switching between DSD and PCM tracks?   Is DoP used by Apple due to the lack of an ASIO driver for any of their players?   Does J-river also use DoP due to the lack of an ASIO driver like the one written with Foobar?
 
I apologize for being a little anal retentive here,  just want to make sure I am getting things clear and appreciate everyones patience.

 

[technobear]

Thank you for the excellent schooling by the gurus at iFi regarding the whole DoP and ASIO with DSD...   Just to confirm, ASIO and DoP both require PCM as a transport mechanism for DSD over USB correct? 

No. Not PCM. Just PCM-style packets and protocol. There is no conversion to PCM. The PCM-style packets contain DSD data.

 

[audiotweaker]

   
DoP "PoP" and how JRMC gets around this

The problem is that when DoP stops there is no defined "level". After DSD playback via DSD finishes, the DAC output may be at any given of 64 Levels and as no more data is send it will stay there.

 
There is a 1 in 2 chance that the level the DSD DAC outputs is either more negative or more positive than nominal "maximum music level". There is a 3 in 4 chance that the level that remains at the output of the DAC is greater than half the peak level of the Music.

When then PCM Playback starts it starts with silence (empty samples as no data is yet sent).

This empty sample forces the DAC to output 0V. This happens so fast, there is no way to mute this. The DoP Playback has already stopped and PCM is being send while we are still trying to get the mute on.

 
This is the "big pop", it is simply an instant return from X (where X will have a very high chance of being at a very high level respective to the music, positive or negative) to zero.

The way to avoid (or at least substantially reduce) this is click is to play some extra DOP Samples (we are unable to determine exactly how many J-River actually adds as they are able to virtually eliminate this issue) representing silence after the nominal playback is finished. By playing silence the DAC output will return to Zero, so when PCM kicks in it will be at zero or very close, so we get no or a very small click.

The ASIO implementation of DSD incidentally takes care of that and hence has no click. In the case of other DAC Chips that convert DSD internally to PCM before filtering and playback this whole issue obviously does not happen!

 
As so far they represent 95% or more of all DSD DAC's out there, this problem is hence quite rare.

We hope this sheds more light on this matter.

 
The rather loud pop I am hearing (and complaining about) is when the iFI Micro iDSD switches from PCM to DSD modes or changes DSD sample rates (ie. DSD64 to DSD128).  This is with three music player apps on the Mac, PureMusic, Audirvana+, and JMRC.  I just downloaded and installed JMRC 20 (latest version) for the Mac this morning and still get this rather loud pop.  It is not reduced in any way, it is still loud if you have the volume turned up!  I have tried every configuration option in JRMC to quiet or reduce it, nothing helps.
 
If there is some obscure JMRC configuration that will 'substantially reduce' this annoying crackle-pop sound please let me know!
 
Alternatively, if there is a way to play native DSD music on a Mac and/or iOS device without using DoP I would love to hear about it.

 

[audioholik]

  The key difference is that ASIO has its own distinct protocol that packs 32Bit worth of DSD data into a PCM sample but support even on Windows is very limited and does mostly not exist on Apple & Linux.

 
exaSound, Signalyst/HQPlayer, and Decibel already provide ASIO support on Mac.
 
There's no pop when using ASIO, because the protocol was actually developed with native DSD support. And that's why you don't have the bizarre 30-50% overheads (and pops) when transmitting DSD via ASIO.
 
 
Quote:

  In the case of other DAC Chips that convert DSD internally to PCM before filtering and playback this whole issue obviously does not happen!
 
As so far they represent 95% or more of all DSD DAC's out there, this problem is hence quite rare.
 

 
That's quite a statement to make, but I don't think it reflects reality. Most DSD DACs I know of (be it 1bit or 5bit) play back DSD without conversion to PCM.
 
That's not to say there aren't DSD DACs that do indeed use PCM decimation filters and down-sample DSD to lowly PCM sampling rates.

 

[Triodemode]

No. Not PCM. Just PCM-style packets and protocol. There is no conversion to PCM. The PCM-style packets contain DSD data.

Thanks...  I understand that there is no conversion.  I guess my use of the word 'transport' regarding how DSD data passes via USB might have implied some conversion to PCM was taking place.

 

[audiotweaker]

  Is DoP used by Apple due to the lack of an ASIO driver for any of their players?   Does J-river also use DoP due to the lack of an ASIO driver like the one written with Foobar?
 
I apologize for being a little anal retentive here,  just want to make sure I am getting things clear and appreciate everyones patience.

 
Music player apps for the Mac are forced to use DoP because Apple Core Audio and USB driver only supports PCM.  If Apple updates Core Audio and USB Driver to eliminate the need for DoP (hope, hope) we would not have this issue.  Further, if there was a way to bypass Core Audio and built-in USB driver the problem could be eliminated.
 
This is all explained in detail in the DoP Open Standard document.

 

[audioholik]

Quote:

   
Music player apps for the Mac are forced to use DoP because Apple Core Audio and USB driver only supports PCM.  

 
Decibel and HQPlayer are both apps for the Mac and they aren't forced to use DoP. They support both DoP and ASIO.
 
 
Quote:

   
Further, if there was a way to bypass Core Audio and built-in USB driver the problem could be eliminated.
 

 
There is a way to bypass Core Audio; exaSound, Decibel and HQPlayer already did this.

 

[Triodemode]

So if what iFi indicates is correct that using ASIO drivers written for DSD remove the pops by ensuring that a 0 level is maintained between tracks, why then are folks here still using DoP with their music players?  I am reading some mention that ASIO drivers are available on players for Windows and Apple computers. 
 
As stated earlier, I am not experiencing any pops with the micro using Foobar2000 and it's ASIO driver for DSD on an old windows XP machine.

 

 

[audiotweaker]

   
Decibel and HQPlayer are both apps for the Mac and they aren't forced to use DoP. They support both DoP and ASIO.
 
 
There is a way to bypass Core Audio; exaSound, Decibel and HQPlayer already did this.

 
Where did you find ASIO for Mac that works with these players?  At this point, I'm ready to try anything.  Do you have links?
 
Also, is there a solution for iOS devices?