AES and DSD

[skolis]

Not sure where to post this so I'll try here.....
I'm trying to verify something I was just told....
In the process of considering some AES interconnects, I've was told
that AES won't play DSD on EMM Labs DAC2X, and on alot of other DACs. USB Only for DSD.
REALLY!
Hard to believe - but I have no experience with these (still
sorting through a new config).
Can someone confirm or call BS on this?
thx,

[Rod#S]

That is my understanding, native DSD is typically limited to tranmission over USB only although some hardware does allow it I believe. I'm not sure which though. I don't think it matters for DoP transmission thus that would be available over AES.

[audio.bill]

Some DACs support DSD over SPDIF (coax or AES/EBU), but most that do only support DSD64 via this connection. DSD64 and above are generally supported over USB. Of course there are likely some exceptions to these generalities.

[Julot]

There is no satisfying way to do DSD over SPDIF or AES. Even DSD over USB is not pure DSD, but is transformed into DoP, processed like a PCM signal and then "put back" into DSD.

There is no standard for unadulterated DSD. Typically I2S input/output, carried on either RJ45 or HDMI plugs. Lengths need be short.

[audio.bill]

Julot - With all due respect to you, there are DACs that do accept native DSD (not DoP) over USB, some up to quad rate DSD. I know that Playback Designs DACs and the new Bryston BDA-3 do so. Also it is a common misconception that DoP is not true DSD. In DoP the native DSD signal is carried in PCM frames for transmission, but the recovered DSD bitstream is an exact match to the original bits. The conversion does take a bit of processing power but the resultant bitstream that is then converted to analog is exactly the same bit for bit as the original DSD data. You may prefer direct native DSD transmission, but stating that DoP is not pure DSD can be misleading and misinterpreted.

[skolis]

Learning something new every day!
Thanks everyone.

[audio.bill]

Additional details on the DoP standard and its implemtnation can be found here (http://dsd-guide.com/dop-open-standard) for those interested.

[Julot]

Julot - With all due respect to you, there are DACs that do accept native DSD (not DoP) over USB, some up to quad rate DSD. I know that Playback Designs DACs and the new Bryston BDA-3 do so. Also it is a common misconception that DoP is not true DSD. In DoP the native DSD signal is carried in PCM frames for transmission, but the recovered DSD bitstream is an exact match to the original bits. The conversion does take a bit of processing power but the resultant bitstream that is then converted to analog is exactly the same bit for bit as the original DSD data. You may prefer direct native DSD transmission, but stating that DoP is not pure DSD can be misleading and misinterpreted.

Thank you. I stand corrected about the existence of true DSD over USB -- but then am I mistaken in assuming that this is not using the USB norm, the same way you can carry DSD over and HDMI connector, but not following the HDMI norm? You need five wires to carry DSD, whether with RJ45, USB connector, HDMI, could as well be DIN or 3 RCA wires...

And I certainly don't want to mislead and concur with your description of DoP, but I would still say that DoP is not true DSD, exactly for the reason you mention. Indeed no bit is lost but by that standard all connections and protocols are equivalent. But everytime you decontruct and reconstuct an audio signal, you lose a little something, even if you don't lose bits.

[audio.bill]

Julot - I'm very pleased to see that you handled my post so diplomatically, I feared that I may have offended you! The DACs I mentioned which accept native DSD over USB use the standard USB connections, not like HDMI connections which are entirely rewired to accommodate I2S data signals. I don't know the details of how it is implemented, but it is done with standard USB cables and pin connections. The new Bryston BDA-3 is most interesting in that it will accept either native DSD or DoP up to quad rate via USB! I can also accept your premise that even though the exact native DSD data is recovered in the DoP transmission process, there may be something lost in the process. There can be additional jitter in the recovered signal due to the additional digital processing that is required to unpack the data from the PCM frames. This can be thought of as being similar to how transports and digital cables have different sound qualities even though they may be recovering and transmitting the same digital data, since the timing of that data impacts the recovery of the converted analog output.