What is the Sony showing as the sample-rate when playing the 5.1 file? 
It shows DSD 2.8MHz 16.9Mbps rate when Audirvana is set to 6 channels and 5.6Mbps when set to stereo.
So it confirms that Audirvana sends all the channels properly apparently.
Here’s a capture of what serviio sends when playing a DSD 5.1 file (browsed and selected from the Sony receiver UI).
HTTP/1.1 206 Partial Content
Content-Length: 512
Content-Type: audio/dsd
Cache-control: no-cache
Connection: close
Content-Range: bytes 12-523/444092508
contentFeatures.dlna.org: DLNA.ORG_PN=DSF;DLNA.ORG_OP=01;DLNA.ORG_CI=0;DLNA.ORG_FLAGS=01500000000000000000000000000000
Date: Fri, 20 Jun 2025 21:11:35 GMT
realTimeInfo.dlna.org: DLNA.ORG_TLAG=*
Server: Mac_OS_X UPnP/1.0 DLNADOC/1.50 Serviio/2.4
transferMode.dlna.org: Streaming
Here’s what Audirvana sends when playing a 5.1 SACD ISO track (or also a stereo dsf file) and the output settings are set to 6 channel.
HTTP/1.1 206 Partial Content
Content-Length: 16
Accept-Ranges: bytes
Content-Type: audio/dsd
Content-Range: bytes 0-15/437782593
Date: Fri, 20 Jun 2025 22:04:14 GMT
Last-Modified: Fri, 20 Jun 2025 22:04:14 GMT
Server: Darwin/24.5.0, UPnP/1.0, Portable SDK for UPnP devices/1.12.2
X-User-Agent: redsonic
Connection: close
Not sure how important the specific dlna options are in the HTTP envelop.
Could that be it and the Sony is very picky?
I assume the rest of the HTTP message itself is just a copy as-is of the DSD file content, but I have really no clue. I didn’t get into learning how it is actually streamed.
While I was looking at the HTTP traffic, I noticed that Audirvana Origin converts the FLAC and AIFF files to audio/wav instead of using the audio/x-flac and audio/aif like Jriver does.
the AIF works fine with 6 channels, but the 5.1 FLAC is only playing the 2 front channels when played from Audirvana.
Aren’t we having so much fun with this DLNA standard, are we? 
There are distinct differences between UPnP protocol and DLNA protocol… DLNA is very device specific… much like products that only support proprietary implementations to suit their Control UI which implement elements of UPnP protocol in their software.
I avoid network based digital-audio for critical playback… 
Serviio uses the DLNA standard. Audirvana, as far as I know, uses the UPnP AV standard. (Happy to be corrected if I’m wrong.) I guess the Sony likes DLNA better.
@mimizone … Possible solution for anybody using an AV receiver for DSD 5.1 playback with Audirvāna… 
From the Audirvāna ‘Knowledge Base’ “How can I connect my device to Audirvāna?”
HDMI
For example, you can use HDMI to connect your computer to an AVR and enjoy multichannel playback with Audirvāna. If you do not have a PCM/DSD sample rate available, please look at your device’s manual or contact the manufacturer.
How can I connect my device to Audirvāna?
unfortunately, I believe not a single Operating system, nor video card driver (open source or proprietary) implements the DSD over HDMI spec. None… It’s so sad and a testimony of the DSD failure… I would love to have just a raspberry pi as an end point doing this. But there is not enough interest from users for this to justify spending time for the developers. Only a few receivers implemented DSD over HDMI, and only a few people use SACD/DSD dumps or care about being DSD native all the way.
I believe you are mistaken about the transmission of 5.1 DSD via HDMI protocol from the computer platform HDMI bus to an AVR that supports multichannel DSD via HDMI … It’s really a function of the SACD DRM that is supported by the HDMI bus protocol and implemented in the AVR… Why don’t you ask the Audirvāna team about the HDMI support for multichannel DSD.?
I believe you are mistaken about 5.1 DSD music aficionado’s…
https://www.nativedsd.com/quality/dsd-64fs/?filter_channel=5-1ch-surround-2
Oh thanks for the pointer.
No clue how they make this work on a computer!?! But I need more details, like a list of compatible devices.