DSD data sent to the Rossini over RAAT: Is it encapsulated in DoP or not?
The release notes from Mosaic 1.2 says “DoP was dropped from the signal path” which is unclear to me: a real change or cosmetic? Or was it always NOT using DoP?
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Yes it’s DoP; dCS doesn’t support DSD-Direct (non-encapsulated DSD). Plus, if I’m not mistaken, Roon only support DSD-Direct over ASIO Drivers on Windows, not over Ethernet.
I can’t remember how the DSD streamed “signal path” looked like before, but I’m guessing they just removed the DoP tags since it’s actually just an capsulation, not a protocol conversion.
Ok makes sense. Given Ethernet is packets rather than a continuous stream, there would be a need to somehow encapsulate the signal and one might as well use DoP since PCM is all worked out already.
That’s interesting; since Roon is sending the data via RAAT, there’s no need for them to use DoP when they use a custom proprietary protocol that may be more efficient.
That’s what I had assumed was meant because the version number of the Roon Core has been incremented.
The SDK - the piece of Roon code inside the network card - has been updated. However, the item in the release notes about DSD is purely cosmetic I think.
Well, yes, technically, RAAT doesn’t require an additional framing of the .dsf/DSD bits with DoP. In fact, neither does TCP on it’s own; which you can see in action every time you copy a .dsf file across say from your NAS to your PC for example - that’s DSD being streamed over TCP (with SMB or any other network protocol managing the transfer).
However, unless I’m not mistaken, all I/O on the current dCS platforms are AES3 framed; evidenced by the choice of AES3 interconnect for the Transport-to-DAC for SACDs for example (as opposed to FireWire on both previous generations of dCS’ flagship stacks). Including from the streaming board into the rest of the system.
Which I believe is also why dCS was able to “so quickly” invent DoP as soon as DSD streaming become a thing; because they were already doing exactly that internally on the Vivaldi stack back in 2011/2012! 
So, requiring DoP framing for DSD coming into the dCS platform makes sense.
Definitely agree with Miguel, the Roon signal-path DoP tag removal is a cosmetic change only.
Separately, “DSD-direct”, (or “direct-DSD”, or native DSD, whatever you want to call it) is actually a 32bit framed data transport format (at least as implemented on XMOS/ASIO). I believe it’s similarly framed over Ethernet/TCP/DLNA for DACs which support native-DSD over Ethernet.
Unlike JMRC, I believe Roon/RAAT does not support native DSD over Ethernet (yet?), it’s DoP by default over RAAT, and no choice to disable DoP (except when a DAC is USB connected with ASIO Drivers).
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Well that’s just it, we really don’t know because RAAT is entirely proprietary and it could well be something else to ensure compatibility for Roon’s own purposes among their various Core implementations; they could be using sftp or scp for all we know. 
Regardless, I suspect you’re right.